I like friend and foe far more than engage and ignore. A foe isnt someone you ignore. Ignoring is what builds bubbles. A foe can often be right even if you disagree.
People I want to ignore I usually disagree with as well, but that's not the problem: the problem is they are repetitive and boring.
A foe is also someone you might preemptively punch in the face if they get too close before you could determine if they actually meant you harm right then.
I'd prefer not to label things such that I'm justifying the label's negative potential by the disproportionately small "even if" range of positive ones.