Exactly, this is not a good PR for him because it is a Republican sponsored bill. This is political football. Sad! He likes ESCs, backs it and doesn't want to appear conceding to ASCs. Sad!
The bill becomes law either when the Pres signs, or 10 days after it is passed which would be 10 October. I agree that it would have been nice if he signed it today, but I don't blame him for missing the opportunity. It would be a missed opportunity if he didn't fight the recent judges ruling and let the issue of stem cell research funding die out.