I understand it is an assumption that all shares distributed were sold, however I think it is a fair assumption, considering the OS was maxed out last January, during those few days of large volume, in which we had minimal price movement. Considering, the OS was increased to the max over heavy volume days, IMO it is fairly good assumption that all shares distributed during that time were sold during that run.
It would be quite odd for lenders to not take advantage of that opportunity.
If the OS had increased after that run, then that would be a different case, and there could still be shares out there. However, that is not the case, and the shares were available to dump during that high volume, minimal pps increase run.
(And yes, the float question is valid. There was what 800 million in the float that could be sold?)