Illogical. If I were short OPK, there is nothing I could do in PBTH to close out my short "cheaper."
If I went long PBTH I would essentially be hedging my short. Once I sell my shares back I'd simply be short again. This would be no different than closing my short position and opening it back at a later date.
The run up is due to OPK going live on the Israel markets tomorrow, and the positive news that has came out this week. Of course some of it is shorts covering, but who wouldn't cover at this point? Only guppies.