I'm not well versed on the 2.50 rule, but just from a numbers viewpoint, if you had shorted SFOR at even .03, your max profit would obviously be that much per share. There would seem to be many more companies with greater shorting potential than that, I can't see how making that little per share would move anyone to take the risk.

There are always rumors of naked shorting through Canada, where it's allowed, but you just can never find proof of it. In the US, even here:

http://nakedshortreport.com/company/SFOR

there's none.