Nothing Kimmel said in the quote you provided is untrue. His statement is about their actions in response to the event, not anything to do with the actual sentiment of the shooter.
I guess you didn't follow updates to the story. I turns out that someone who was a "huge Trump supporter" in 2020 can develop romantic feelings for his trans room mate in the intervening five years since -- and feel a different way on issues.
Only by stretching the facts to distortion can anyone claim the gunman was one of Maga's own in 2025.