You don't need to treat them like they're acting like a "tough guy", they're already saying they would get their ass beat if they tried something like this.

I definitely get the sentiment too: Of course, I have no idea how I would actually react in a situation like this, since I've never been in one. However, I have a hard time seeing myself idly standing by. I would definitely have a very strong desire to do something, but I don't know if my sense of self-preservation would prevail over my sense of justice or not. Point is, none of us are trying to come off as some "tough guy", we're just echoing a feeling I think many people have: That we think it's hard to imagine just standing by and watching someone else be beaten like this. That doesn't mean we're claiming we would do anything, but for myself I can at least say that I hope I would do something, and that I have a hard time imagining that I wouldn't.

Been to plenty of protests. Luckily the police have been civil, or like I said, my life would be significantly worse or over at present.

True. But what if that person was beaten to death, and you could have prevented that by intervening. That would be changed by getting beat. Or if multiple people were to aid you, the cops could be moved away.