I think the best part about it is that it doesn't matter what Bush did, he'd be screwed no matter what he did. If he didn't veto the bill, he'd get barbequed by the fundie nutters who got him elected in the first place. He'd lose enough support for the Republican party that they'd probably get defeated next election, unless he could rebuild theological credibility in the next two years, and that's a very difficult sort of credibility to build.
So his other option was this. That's a setback for science, but consider who else he pissed off. He angered everybody in his constituency who could be helped by such research, or more accurately the slim subset who actually understand the issue at hand well enough immediately, and within the next few weeks probably most of those who needed the help as the Democratic PR machine might actually get cranking this time.
So no matter what Bush did, he'd lose a large chunk of support. And given how thin his last victory was, he's probably salted his feet- uh, sealed his fate. (Bonus points to anybody who gets that obscure literary reference) Or at least that of his party with regard to the next election. But then, voters have short memories, and there's still more than two years to go for him to get forgiveness.
It's really pushing the science-Christianity relationship to one characterized as "versus", however, and that's one of those things that would be interesting and entertaining to watch if I didn't have to live with it.