Take a step back from that understanding and think about why the US chose a close ally like that in the first place, why they keep choosing and uplifting close local allies like that all over the world. This isn't some little whoopsy "someone didn't do their research" sort of thing: it's an active choice on the part of the US to cultivate the most monstrous allies they can find everywhere they can, and to incorporate the violence these allies will eagerly commit on behalf of the machine of imperial hegemony into the capabilities of that machine itself.

Why did the US side with Saudi Arabia? For the same reason that they committed genocide on behalf of Syngman Rhee following his massacre of 300,000 suspected dissidents, for the same reason they hooked up former Nazi intelligence agents with Suharto in Indonesia and provided material support for his campaign of genocide, for the same reason they funded reactionary militants and dictators across the Americas whose crimes are so grotesque I can't even touch on them without a dozen content warnings.

The US chooses allies like Saudi Arabia and Israel because virulently misogynistic, racist, and elitist factions are the natural allies of America's own virulently misogynistic, racist, and elitist hegemonic ideology. It is bad for the US to make such allies, but the reason it does so is because it is like them and so they make for an easy and natural extension of its imperial power.