Before everyone gets too carried away with this ...
Saw a similar attempt at this just recently on another board, their whole MO was how they were going to screw the MM's by keeping their shares out of their hands ... The stock tanked anyway, in fact, it seemed directly correlated to the efforts.
i just checked with my broker. even in margin accounts, IF YOU SAY NO, they MUST keep your shares AWAY from the shorts. i double and triple checked.