If the government sent them there (embassy, state dept employees, other federal employees or contractors, etc) then certainly the government has an obligation to get those people out.

But for those the government DIDN'T send, once the State Dept issues an order that they should leave, I don't see that the US should have an obligation to get people out who had the ability to get themselves out but failed to do so.

To put it another way, if someone deliberately ignores the advice to get out, and then finds himself in trouble, is the government obligated to put someone else at risk (i.e. the "rescue team") to extract the person who shouldn't have been there in the first place?