You're right. He was under pressure. And he caved to the demands of the party rather than hold true to his stated convictions. Do you find that admirable? I don't.
They want reelected. When reelection is more important than the principles that they ran on, it's time to replace them. They're infected with Potomac Fever and the only cure is to get them out of DC.
No, I don't, and I said so at the time.
The problem is: the alternative to re-electing Sen. Santorum is almost certainly worse.