A judge ordered Pentland to pay a $1,087 fine or spend 30 days in jail for the misdemeanor charge, court records show.
An attorney for Pentland said he is looking into challenging the decision.
“We are of course disappointed with the judge’s decision and are looking into further pursuing legal remedies to challenge the decision,” Benjamin Stitely said in a statement.
“As quoted in several of the local media outlets, Mr. Pentland stands by his right to defend his family and home from a genuine treat (sic) and is deeply hurt by the situation,” Stitely said.
The victim “stated he minded his own business before Pentland approached him,” WIS reported.
In the video, Pentland is seen pushing the young man shortly after Pentland tells him, “You are aggressing on the neighborhood.”
“You either walk away or I’m going to carry your a** out of here,” Pentland says.
“I did not do anything,” the young man responds.
“I am about to do something to you. You better start walking,” Pentland says in the video. “You’re in the wrong neighborhood m*therf**ker. Get out.”
Pentland’s attorney claimed there was a “lack of investigation into the background factors regarding Mr. Williams’ actions leading up to the small portion of the encounter captured in the viral video,” Stitely said in the statement.
The Richland County Sheriff’s Department said in April there were two previous incidents reported to deputies involving the young man, one allegedly involving him touching a woman without consent. The other involved him allegedly picking up a baby without permission.
The department claimed the victim has an “underlying medical condition that may explain the behavior exhibited in the alleged incidents.”
CNN has reached out to Fort Jackson for a comment on the ruling.
CNN’s Raja Razek, Paul P. Murphy and David Williams contributed to this report.