They don't have as large of a pool of shares available to work with. They needed ~8MM-10MM shares to accomplish what they did last time, and they don't have that many shares available right now.
They'll trigger a few people who bought in below $7 to sell and take their gains, but we'll see how hard they try. The painted themselves into a corner hoping to find a way out later. We'll see what comes of it. Personally, I think we MAY go down a few bucks, but shorts will end up losing big in the end.
Remember that every share they short needs to be replaced eventually, and the price has been gravitating toward $12 every time they stop shorting for even a day. Shorts will gain $1-$2 today to lose $3-$4 tomorrow. Seems like a bad idea, but it's their choice to make.