Whites were talking about blacks in general. Some black people took it as though they specifically were being targeted. If white people don’t feel comfortable running alone at night because blacks can be predators, black people in general should listen. When I hear that, I don’t take offence. I’m with you, I’ve never done anything. But we should be trying to figure out ways that whites can feel more comfortable around blacks. Whites shouldn’t need to feel like they have their guard up, and listening is the first step.
Every time you hear a claim about women/men replace with white and blacks, if you sound like a racist asshole, then you're being a sexist asshole. This also applies for other stuff, including just reverting roles, if just by doing that you're able to make your argument sound straight from the KKK, you know it's a bad argument.
That's not to say that women shouldn't feel like that, or that there isn't a problem in our society, but the same can be said about white/black situation. The difference is that most people (at least non racist assholes) understand that a higher criminality among black people has nothing to do with their skin tone, and is instead a consequence of historical factors perpetuated by social injustice, so they understand why generalized statements such as the one you made are problematic. But with the men/women people in general think it's different, they think that men are inherently more violent or whatever, so their broad statements get less judgement, let's not forget that up until recently that was also the general consensus about race as well.
In short if you do broad generalizations like that you ARE being an asshole, and people will feel attacked. And what's worse is that those people are more likely to then align with someone who opposes your views which oftentimes means right wing Nazis just because they're not attacking them.