I'm merely forming an analogous argument to yours: mine is in support of subsidizing terrorists, yours is in support of subsidizing systematic violators of human rights. If you can point out why the analogy is not valid, please do so.

Re: your edit: at issue is not that the US purchases goods from the Saudis (though it could be argued that we have a moral obligation to impose an embargo), but rather, as the parent of your post suggested, that the US subsidizes artificially low oil prices from the region.