You really have short for brains, spree. LOL!
GMXX didn't run on massive short covering at all, but rather it ran on an orchestrated pump with most of the outstanding shares from the initial private placement locked up to limit the float. Of course, the promoter ICI's shares weren't locked. The 'short covering' was a (ahem) cover story.
Indeed, the smart money--the promoters and those with private placement shares--more than likely sold short as the orchestrated spike peaked, covering later with their cheap shares. The terms of the lock-up and private placement were never disclosed publically, so we don't know if there was an anti-shorting provision. From the price action at the top of the spike, I'd wager that there was no such restriction.