Do GMs get paid or compensated for this position? If so, then no, they shouldn't be in any factions because that's a gross example of bias whether intended or not. Personally, I think it's entirely unprofessional. I don't have anything against the GMs on this server. I don't personally know anyone and I don't think I should.. hence why they are a GM and not a standard player in the first place.
Let's all be honest here and let me use an example. Let's say HangOver and Xpendables have a TW on Saturday. If a GM loves HO, but hates Xpendables and decides to ban/mute Xpendable members directly before the TW for speaking anything in world chat, is that considered bias? Definitely. Is anything really done about it? Doesn't seem to be so. If a GM doesn't receive any actual punishment for giving free items or abusing ban/mute powers before TWs or events, where will this stop? Where is the unspoken line of limitation? Answer? There doesn't seem to be one, and this problem won't go away even though several people (players and other GMs) will just turn a blind eye to it and pretend it doesn't actually effect gameplay when it most certainly does.