if you go and pay him, he\'ll play em
Hell, he even played a reggae version of Freebird!
Well, perhaps if he IS playing places that are originals-friendly, he could somehow let it be known that that will be that case. Maybe promote the two different types of shows differently. I understand that he needs to play covers to keep the crowd happy and pay his bills.
As Joe suggested, how about reviving the occasional Diesel Experiment? He really needs a good crowd and venue to make it worthwhile for him to prepare that much for a show.