this stock hasn't shown the strength to get past the 19's yet, and the rsi needs to cool off at some point. They don't run in the red zone forever, especially on the news this one had. I'd be happy with 100% gain as a long and not get greedy. Of course to each his/her own. I'll stay short and wait.
No stock is ever too strong for shorting after a major runup. Just make sure you don't short more than what you can handle. Leave a little wiggle room in case you need to average out. Why not take advantage of retracements when you can. imho.
Because your potential loss is infinite. Assuming unbounded risk is playing Russian roulette (but to each his own), and as ICPT proves, from 60's to currently over $240 in days, can happen when you least expect.