Since when does the accused get to hand-pick the judge?
This is a civil case, not criminal. There is no "accused". If I was in BP's shoes, I'd certainly want a judge who is knowledgeable of the oil and gas industry, and I'm sure that's the argument they used when making this request.
Despite the donations, he's seems to be fair and even-handed when ruling. Unfortunately, that fact is buried in the whargarble.