[Rock Bottom]

Looks like he bladed after Lawler threw him into the cage. (WRONG!)

IF he bladed, which is really hard to tell without different shots, a wild theory might be something along the lines of what CSL said, to try to give Lawler something.

My guess would be, in that situation, that CM Punk probably thought it was really stupid for him to wrestle/squash Lawler. He really went out of his way to sell Lawler's first punch in the match. I think he's just really trying to sell his fist, like "the old man can still punch," rather than just squash/shit all over him like everyone else does in the ring.

I mean, if I were the WWE champion and I were wrestling a hall of famer/announcer that's just there to job for people randomly I'd probably feel pretty weird just squashing the guy. What does it achieve other than cheap heel heat? (which by the way is only being met with silence)

It could have been an accident but I really doubt it. And if it did, as you can see above, why he would do it is just random speculation.