How is it risky to the engineer, as long as he gets paid? Job security, maybe, but that is hardly worth a lot.
And even if your bosses give you a great recommendation, it can sometimes still hurt your career. After all, the company failed. Maybe these bozos recommending you were idiots too, and the fact that you were working for them means that you were also an idiot.
This attitude is thankfully pretty rare in Silicon Valley, but it can be quite common in other parts of the world. Early employees actually run more resume risk than founders do, because if the company fails, the founders can at least put "Founder & CEO" on their resume, but the engineers can only put "Software Engineer, company you've never heard of."
Anyway, it is all in the upfront negotiation. If engineer is unhappy with the conditions (ie not enough stock options), he should leave. To complain afterwards is lame (oh, they made a shitload of money - if only I had negotiated for more stock options...).
So? Every for-profit company I worked for from early 2001 through 2008 failed. Who blames the programmers for the failure of a company? In my experience, virtually no one.
One aspect was that he was having trouble finding interesting projects to work on. The JDAM precursor where he teamed with a major aerospace firm was I think lost due to politics. Simple GPS systems were a step or three down from that but were nonetheless more interesting than the other work he had been able to find for some years previous to that (losing the JDAM precursor contract was a last straw sort of thing).