The whole point of friend/foe system on Slashdot is that foes' comments are less visible, and friends' are more visible. It's basically a way to say "this person tends to say ridiculous things, and I don't care to read more of them" and "this person tends to say interesting things, I'd love to hear what they have to say on other subjects".
So if your approach is to "try to avoid interacting with them", it just automates that.