But if the 75-year-old veteran lost his cool at the Louisville rally, he did so at the "urging and inspiration" of his President, Bamberger alleges in a lawsuit against Trump.
"Trump and/or the Trump campaign urged and inspired Bamberger to act as he did," according to the Ohio resident's claim, which was filed in Louisville federal court on Friday.
Bamberger's lawsuit is the latest against Trump -- no stranger to legal claims -- in connection with the raucous March 2016 rally.
US District Judge David Hale ruled out that the attackers were Trump agents but said it's plausible the would-be President incited a riot. He denied motions to dismiss or strike portions of the complaint.
The three protesters -- Kashiya Nwanguma, Molly Shah and Henry Brousseau -- say they were assaulted while attending the Louisville rally for the purpose of "peacefully protesting Trump," according to Hale's ruling.
Nwanguma was carrying a sign with Trump's head on a pig's body, according to multiple news reports.
'Urged and inspired' by Trump
Now Bamberger is coming after Trump, with a claim filed by Louisville attorney Stephen Pence that alleges the then-candidate and his campaign "repeatedly urged people attending" his rallies to "remove individuals who were voicing opposition to Trump's candidacy."
At some rallies, the lawsuit says, Trump and his campaign "promised to pay the legal fees of those who -- following Trump's urgings -- removed the protesters."
Bamberger admits he "touched" a woman but denied the assault, according to court documents.
"To the extent that Bamberger acted, he did so in response to -- and inspired by -- Trump and/or the Trump campaign's urging to remove the protesters," the lawsuit says.
"If Bamberger is adjudged liable to Nwanguma for his actions, Trump and/or the Trump campaign should be adjudged liable to Bamberger in an equal sum, because Trump and/or the Trump campaign urged and inspired Bamberger to act as he did."
'Immune from suit because he is President'
In court documents, Trump's attorneys denied the allegations, asked the court to dismiss the case and argued their client is "immune from suit because he is President."
Trump's legal team also asked that the President be awarded costs, expenses and attorney fees.
The President's attorneys admitted their client said "Get them out of here" during the rally -- referring to the protesters -- but said he was not directing his comments to the crowd.
And, they said, Trump instructed his security, "Don't hurt them."
The three protesters accuse Bamberger and Matthew Heimbach, who was representing the white nationalist Traditionalist Workers Party, of assaulting them, according to Hale's ruling.
Nwanguma, Shah and Brousseau accuse Heimbach and Bamberger of assault and battery. They also accuse the Trump campaign of incitement to riot, negligence, gross negligence and recklessness.
The negligence claims arise from the plaintiffs' allegations that Trump knew his supporters would attack protesters. In particular, Trump's directive to eject a black woman was reckless, given the presence of a white nationalist group in the audience, the complaint says.
The three seek unspecified punitive and compensatory damages.
A charged rally
Video from CNN affiliate WLKY in Louisville
shows several protesters yelling at Nwanguma, an African-American. A man in a red "Make America Great Again" hat, who resembles Heimbach, shoves her multiple times, putting his finger in the University of Louisville student's face and yelling. Another man in a military-style uniform then continues shoving her through the crowd.
CNN affiliate WDRB in Louisville
reported in July that the Louisville Metro Police Department issued criminal summonses for Heimbach, Bamberger and Joseph Pryor of Indiana, charging them with misdemeanor harassment for making physical contact with Nwanguma.
Nwanguma alleged she was the subject of racist and sexist slurs during the incident, WDRB reported. Four other protesters filed complaints after the rally, the station reported, but prosecutors declined to press charges.
According to the federal ruling, Heimbach shoved Nwanguma before Bamberger struck her. Heimbach also shoved Shah, while an unknown attacker, believed to be with the Traditionalist Worker Party
, punched 17-year-old Brousseau, a high school student, in the stomach, the ruling says.
Rally attendees continued pushing Shah, even as she made her way to the back of the convention center, the ruling says.
As the melee unfolded, Trump told the rally, "Don't hurt 'em. If I say, 'Go get 'em,' I get in trouble with the press," according to the ruling.
Men acknowledge pushing
Bamberger, who wore a Korean War Veterans Association uniform at the rally, later conceded in a letter to the group that he "pushed a young woman down the aisle toward the exit," the court ruling states. Though it's not mentioned in the ruling, Bamberger also said in the letter that he sincerely regretted pushing the woman.
Heimbach, too, acknowledged his role in the incident, writing in a blog post that he helped "the crowd drive out one of the women," the ruling states. Reached by the Southern Poverty Law Center's Hatewatch blog last year, Heimbach did not express remorse.
"This is clearly a political prosecution, and it's a miscarriage of justice," Heimbach told the blog
. "I'm not surprised we have a biased system that favors violent and radical leftists instead of holding up justice for everyone."
In response to the protesters' lawsuit, the Trump campaign said that no riot actually occurred, that Trump's words amount to free speech and that Trump was not addressing audience members -- but rather, security personnel -- and did not intend for violence to erupt.
Violence was a repeated theme during Trump's campaigns with both Democratic presidential candidates addressing it and with GOP Sen. Marco Rubio, an early presidential candidate, expressing concern that someone could be killed
at one of his rival's rallies.
During one presidential debate, Trump said he did not support the violence happening at his rallies and explained its roots.
"When they see what's going on in this country, they have anger that's unbelievable. They have anger. They love this country. They don't like seeing bad trade deals. They don't like seeing higher taxes. They don't like seeing a loss of their jobs," he said. "I see it. There is some anger. There's also great love for the country. It's a beautiful thing in many respects, but I certainly don't condone (violence) at all."
Presented with some of his own remarks that seemed to condone violence at the rallies -- including one in which he said to hit a protester and promised to pay for the legal fees -- Trump turned the blame on the protesters.
"We have some protesters who are bad dudes. They have done bad things. They are swinging. They are really dangerous and they get in there and they start hitting people," he said, claiming it was often local police who removed the protesters from his rallies. "It's not me. It's usually the municipal government, the police, because I don't have guards all over these stadiums."