I think this is less binary than the article suggests. In addition to expression and repression of anger, there is also "letting things go." When you can forget about something that made you mad, you get the satisfaction of knowing you didn't let it phase you (arguably better than catharsis) without all the problems associated with revenge and obsession.
I really like this paragraph from http://paulgraham.com/top.html:
Turning the other cheek turns out to have selfish advantages. Someone who does you an injury hurts you twice: first by the injury itself, and second by taking up your time afterward thinking about it. If you learn to ignore injuries you can at least avoid the second half. I've found I can to some extent avoid thinking about nasty things people have done to me by telling myself: this doesn't deserve space in my head. I'm always delighted to find I've forgotten the details of disputes, because that means I hadn't been thinking about them. My wife thinks I'm more forgiving than she is, but my motives are purely selfish.