I don't mean to "Not all men" this, but I wish we would stop treating behavior like this as a normal part of the male psyche. It's not. It's seriously disturbed. It's an unfortunate consequence of the Internet and any area where you have a large audience that a small active segment is going to produce a large impression.
Yes, maybe your friend and even most men feel differently when a woman criticizes them than when a man does. No it is absolutely NOT a normal, male response to start making rape and death threats because of it.
I think these responses are a combination of seriously disturbed individuals and literal or mental children who haven't yet fully internalized that there are real live human beings on the other end of the keyboard and are trying to be shocking.
I think making a few examples would deter the idiots who think this is amusing. I mean, that one kid in Texas made an offhand, sarcastic comment about shooting up a school and got himself arrested within a couple of days. It would be nice to see police take other threats as seriously.