Welcome to FR. There is a small contingent of loudmouthed firebrands here who seem to think it "principled" to enable their worst enemy to take the Oval Office. Sort of like the kid who threatens to commit suicide to get back at the girl who spurned his advances. It is a form of adolescent acting out-- in this case, rebellion against the fact that no candidate is perfect, and that one necessarily has the duty in a democracy to vote for the best available candidate. A few freepers are too young and naive to accept that adult responsibility, and predictably, they blame the candidate instead of themselves.
Pay them no mind. Most of us have the sense to realize that half a loaf with McCain is better than starvation with Obama.