I don't think that he's ever seen doubles as anything more than an opportunity to get extra match time - though that must be a little disappointing to his doubles specialist partners! I agree that taking it too seriously would get in the way of his singles ambitions.
I'm not so sure the doubles partners are disappointed: without him they wouldn't get entry at that level at all... so I'm sure for that alone, as well as the possibility to be around better players which inevitably motivates and teaches by example, they are grateful...