I think that can and does happen, yes. But I wouldn't put the blame on the apparent unassertive person necessarily. The responsibility for these angry attacks falls on the angry person.

But having an air of self confidence ie., being composed, looking people in the eye when speaking, having principles, being assertive etc., yes, may cause others to think twice before stooping to taking anger out on innocent targets, sure.

I can't think of anything else to add to that at this time.