They'll have no trouble at all covering. But yes, if they sell naked in the course of making a market, they do have to cover. Usually they do that within minutes. If more time is required, they have that too. Officially, stock, whether bought or sold, is to be delivered within three days.
If that doesn't happen, the result is a failure to deliver. Fails to deliver occur frequently in the normal course of trading, and they aren't always caused by shorting. There can be a number of reasons. In this case, stock won't be delivered because of the suspension.
But when a security is trading normally, MMs have 13 days to make the delivery. If there are threshold fails, and the stock ends up on the Reg SHO list, after the 13 days have passed, the MM cannot make any more short sales in the issue until he's cured his old fails.
Short squeezes occur when a stock is going up so fast that MMs (and retail shorts) can't cover. Their clearing firms issue buy-in notices. At that point, they must buy at whatever price they can get.
But that won't be happening here.
