Even if Cole gave up multiple runs, it wouldn't have hurt his current market value. He's going to be a very rich man. I bet he absolutely wanted to pitch -- just common sense. The best pitcher should not be held back in that situation (with two days rest).
That game was insane. Greinke was working on a one hitter with one out in the 7th inning, a low pitch count, and a two-run lead. Max somehow managed to grind out five innings and give up only two runs, with so many LOB. Earlier in the series Corbin was doing his best impression of Gio Gonzalez. Now he proceeds to carve up the best hitting line-up in baseball.
In reality, I think you're right. But, Cole's post-game remarks really bother me. Cole may end up being a hall-of -famer, but he's never going to be loved like Cal Ripken, Derek Jeter, or even Ryan Zimmerman. I'm sure that Harper is second guessing himself now. Sure, he can convince himself otherwise by looking in his bank account, but there's more to life than money...