Honestly it makes sense, he has a better shot at running for and holding on to the governors house than he did that senate seat.
If he was smart, and he really isn't all that smart, he would switch parties now or at least declare he is Independent. MA does elect Republican Governors (evidence: Mittens) but if he switches and gets elected then after he serves he can go back into national politics from MA and never have to worry about winning again (if he does a decent job as Gov.)
Since he tried so hard to distance himself from Republican policy in the recent Senatorial election, switching parties would be fairly easy for him.
I just want to make out with him.
I used to think he had a nice, warm, moist and inviting anus, but now, not so much...