Most importantly: SEC suspending trading in a company doesn't eliminate a short sellers' obligation; they still owe the shares they borrowed.
But it's mostly an academic problem; no one shorts penny stocks for profit anyways because the margin requirements are so onerous it's just a giant waste of equity. You'll make more money guaranteed owning US T-Bills than you will tying up your equity to short MAXD shares with reverse-leverage of 1:500,000
The only people who believe that MAXD is being systematically shorted are fools who believe management's lies. They simply cannot accept they gave their money to crooks.