This kind of non-factual pumping post is as silly as the bashing ones from sense.mrcommon and his like, but in the opposite direction. Brokers do NOT adjust their margin requirements in anticipation of events. They sometimes do so after the fact, but not beforehand. The margin requirement for ARNA at Schwab has not changed for a long time, and it won't change in the coming weeks.
Brokers are already on the hook for about 10 million short shares that they probably won't be able to get under 12. Then there are all those calls...whoever bought them is about to lose a lot of money. I would hate to be on the wrong side of this trade. This could take down a brokerage.