I cannot understand how Vivendi/Sierra would let him go over a performance related issue. It was likely either money related or politically motivated.
He may have been making too much money. He is Jewish, after all, and certainly negotiated a good salary.
More likely he wanted to do something with the brand (like, say, involve the community to the degree he did) that upper management disagreed with.
Who knows. Welcome Michael Cowan. Do our much-loved game well, and please involve yourself with the community as much as our Weasel did.