I've never heard of that case, and goes against everything that I've heard from actual trans people, but even if it was true, one case does not make it the same for everybody. There were probably other factors going on at the same time, and they just either chose to report it as being due to T for transphobic reasons, or the assaulter tried to use T as a get-out clause for his actions.
[EDIT: just noticed that you said "trans men" rather than a specific trans man. I would still call it out as BS, the only time I've heard of trans people getting more violent on T is in articles reporting it's side effects, but every person on here who's experiences on T I've read about have been the opposite to that. I'm not sure if this makes any sense actually, I'm kinda all over the place at the minute. Sorry.]