Sarver most likely did not say "Trade Kurt Thomas by whatever means necessary." He probably said, "We need to save some money, make a trade to do that."
KT was, at the time, when you talk about the ratio of contract to contribution, one of the most overpaid players on the roster. Looks like the only way Kerr could rid ourselves of that contract was to add two unprotected picks. Horrible move, but even if it came from Kerr, Sarver did end up approving it--so there is plenty of blame to go around, and not just on one person.