Sadly, Zarathur may be one of the Chaos factions biggest weakness. Sure he is pretty strong, but you need to keep him at a planet for his ability and He has the lowest HP (I believe anyway) of all of the warlords. It takes one good slam of 3 damage for the chaos player to really play timidly, which could destroy your strategy.
Good point. However, the picture I'm getting of Chaos is that they are the "devil may care" faction. They aren't fancy, they are going to come right at you, multiplying damage by any means necessary and not be overly concerned with anything else. Obviously, this is Chaos' background flavor. I think booored's theory may be correct in that he will rely on doing as much damage as possible before the same can be done to him and/or having the threat of other heavy hitters to make an opponent think twice about where to attack. Chaos tactics look like they are geared towards frontrunning, not so much towards playing even or from behind for too long.