I think it's pretty reasonable to assume an investment banker isn't going to be much help to FB employees in finding a new job. Claiming that "Facebook will be known for having hired mediocre sell-outs a few years from now." is at best a baseless slander. How in the world is that not in bad faith?
Spreading misinformation to aid one's short position is a much worse case of bias, in my mind, than what I've said in defense of the company.