I don't think it's all about money, but that, obviously, plays a significant role. It goes back to the advice that Tim gave Felder in their last phone call after Felder's firing - "why couldn't you just sign the papers like everyone else ..." I don't think Joe or Tim agree with every decision that is made on the band's behalf, but they both accept that it is not their role in the end.
Let's face it - if it wasn't for the money that Tim made from his Eagles gig, he would likely not have had the money it took to finance the Expando project or subsequent tours. I highly doubt that this has been a money-making venture for him, but it was a wonderful creative outlet. His "Eagles" $$$ afforded him an opportunity to make this album on his own terms that he may not have otherwise had. I'm betting there are plenty of struggling musicians out there that would die for the same chance.