Indeed, Russell was commited to do the show adn then bailed out for other commitments. Like in every situation in life, there are more reactions to the two extremes, like "It's totally cool bro" and "OMG I want to kill him", I don't think Arjen "hates" Russell but since he's estabilished enough to be able to do without him, well, he just will I guess, and work more with singers who will be more than able and willing to commit to him.