Why is the AARP Running This Ad?

I spent a quiet day yesterday, cleaning my closet with the television on. As a result, I got to see this ad, over and over:

Now this is an odd little ad.  It's not in favor of anything in particular.  Nor does it solicit membership in its group.  Its purpose seems to be to defend the AARP's decision to endorse this health care bill, which John McCain blasted on Saturday.

Why does the AARP need to do this?  I infer that despite their happy-face public comments, they're having a lot of troubles with the membership over this endorsement, but they can't really come out and enumerate the goodies that they scored in exchange for their two-thumbs-up, because that would simply reinforce the notion that the AARP is a gigantic money-sucking cancer on the American body politic.  So instead . . . soft focus blandishments.  I'm a little skeptical that this is going to improve matters for them, but at least it probably doesn't make them any worse.