Stocks can't run quick if there isn't buyers! Whether those buyers are covering a short position or going long, they still drive the price up.
FDA decision isn't expected until January - If the stock moves up between now and then in anticipation (my best guess) shorts should have waited. If it hangs around $3ish, shorts still have to wait 5-6 months for any sort of substantial movement.
In the end, short or long doesn't matter - place your bet. Only one will win - and it won't be until the FDA decision.