Bumps are based off of TABs not activated pilots. So if a TAB has been assigned under the SFO MOU they can bump the crap out of SFO.
I don't know how many of the 400 are left untrained to bump. But you're getting setup for an expensive lesson.
I find it funny how S-UAL pilots always explain it away when they are possibly about to be hosed. Wouldn't you rather see the TPA, UPA, SFO MOU, and ISL enforced?