I think it's also important here to point out that he usually nominated the person who was most likely to go anyway. That made the others think he was somehow all powerful and getting people evicted, when in reality he was just good at determining who wasn't popular on the outside. A lot of them in there (particularly Heidi, Ed, etc) had a completely warped perception of who was popular on the outside. He was lucky that his perceptions were right, it was the others that gave him more power than he really had.
He obviously did stir the pot, which caused HMs to react and get into arguements, but that's their own perogative. If they cant control their own reactions to him then they probably deserve any falls from grace they have at their own hands. People's real character is shown when they're under pressure, not when everything is going smoothly. I for one was happy we got to see that. But regardless, Tim was completely open with all of this. He told the audience what he was doing and the HMs themselves when one of them actually bothered to ask him instead of just bitch in fear behind his back. I remember once when Jade straight out asked him if that's what he was doing and he just said yes, no coverups or trying to manipulate the situation to make him look like a victim. He admitted himself he had no master plan, he just caused chaos and let things settle where they may. And what's wrong with that? Did any of you really want to watch them sit around singing Kumbaya?