I don't believe Xander Kabrinski was the sole cause of the destruction of Ikalak from within. There were a lot of politicking, and our first ruler, and a few others in positions of power made some decisions which were not taken kindly by all the other nobles. That being said, I think Xander the character made some choices that were pretty influential in terms of bringing down Ikalak.
1) His first action as Duke was to build a tournament ground. Really? A tournament ground is what you decided to build FIRST in the WAR ISLAND?
2) He appointed himself Margrave of Ikalak, giving himself enormous amounts of power.
3) I'm not a Council member, and am not privy of the discussion, but I seriously doubt the law where a noble is not allowed to have more than one position is specifically targeted at you. It was the outcome of having so many active nobles in the realm, and wanting to spread the power around so that EVERYONE can have a bit of fun, instead of a few players holding multiple positions. Your reaction to this decision, in game and OOC, was to put it nicely, not good. It was becoming obvious that Xander was becoming too power hungry and coming up with lots of excuses to refuse stepping down as either Margrave or Duke.
4) I don't know what you mean that you are not allowed to have any say in who the Marshal of your army is. You know the rule about not nobles not allowed to have more than two positions. You can easily choose any other capable Marshals from your army.
5) I don't know about any micro management, so I shall not comment on that.
6) Finally, and quite importantly, the accusations that Xander was stealing gold from the tax office in one Ikalak's regions. I don't know if this is true or not, but IC, my char had reasons to believe he did. And this was the final straw in the camel's back, it seems.