It should be red if he can back it up with a proper Reference link with proof. Without that, it's just his opinion. He's entitled to have one, and I prefer neutral over red for it.
If we are talking about a lesser evil we are going to agree on this, but my point is that if you don't have proof you shouldn't write that someone is untrustworthy, a liar and has mental problems. You'd better keep your opinion to yourself and not write it on someone's trust page.