alternative  

If black blocks the other way and then covers the cut at , white has a to push out at a and then cover at b (to avoid a snapback); black can use sente to push out at c and take the corner, and the top side group stays strong. Why isn't this played? Too much influence for white along the right? The two black stones seem to keep some aji to offset this. Or have I missed an obvious counter?

Edit: I asked some mid-dan players at the club; they could see no clear reason why it would be objectively bad, but probably to do with the plays necessary to go back and capture the corner, or ko aji.