The thing to remember about Coburn is that he is a golem made of crotchety, and he derives sustenance from people hating him. So he just says whatever the hell he feels like regardless of what his audience will think about it. (In that sense he's sort of the guy John McCain wishes he could be.)
Coburn would be considered admirably forthright if not for the minor handicap of being pants-crappingly insane on most issues. Got to give him partial credit for being honest about it, though.
The best part is "pants-crappingly insane." Take note, CotD hopefuls!