It's not about "appearing noble," it's about having standards for yourself or not. Or to be more dramatic, standing for something or standing for nothing.
You mention a "lifetime supply of dough" would make it easy to turn down something like providing background music for the RNC, but Smith isn't going to starve if he passes on a gig. He's an established professional musician. I mean, Pink Floyd is calling him to do tours, fer chrissakes. I would assume that they aren't the only ones.
And in reading that article I had the feeling that he may have been exaggerating about how much he was paid for the RNC gig to make the story more palatable. Or to provide justification for doing something he thinks maybe he shouldn't have done (since he may have taken flak from friends or other musicians for doing it).
Anyway, it's the old joke, isn't it:
"Would you fuck me if I paid you a million dollars?"
"Well, yes, for a million dollars."
"Okay. Well, would you fuck me if I paid you 10 dollars then?"
"No! What do you think I am?"
"We've already established that. Now we're just haggling over price."
The times have changed, and most young musicians have no concept of "selling out." They got into the business specifically to sell out. So I understand that having personal standards or standing for certain ideals is an old-fashioned notion. But in the not-so-distant past you wouldn't have seen any musician performing at the RNC unless they were Republicans. Unless they were idealistically aligned.
Imagine Woody Guthrie or Bob Dylan or Joe Strummer, someone like that, doing a gig like that and justifying it by saying, "Well, they paid me a lot of money!" It wouldn't happen, not for something they didn't believe in, or that they believed was harmful or even evil. And two of those guys I mentioned were not rich enough to turn down any good payday.
Anyway, like I said, it's a corny old notion now, so who cares. And I suppose now someone will dig up an article about the Clash playing at the Monsanto employee picnic or something. Bob Dylan playing at Saddam Hussein's daughter's sweet sixteen party. Okay.