America has maintained a seamy relationship with Saudi Arabia for decades because of oil. This has persisted even though the Saudis are a repellent regime, and they have been a fount of extremism and the very terrorists who kill us. Meanwhile, our relationship with Iran has been nothing but hostile since the Shah's fall and the hostage crisis. Add that Iran is Israel's bitter enemy and our thinking on that subject basically stops. These problems are bipartisan, and they both lead us to a bad place in Yemen.
But as that piece from the Atlantic reports, Obama's support for Saudi's war in Yemen was less than full throated. Indeed, our support came despite Obama's deep misgivings about our Saudi "friends" and their reciprocal antipathy for him. Remember also that Obama was then trying to negotiate the politically fraught Iran deal, with all its moving pieces.
More to the point, though, Trump isn't merely the latest Republican version of our long-standing Saudi coziness. To the extent we aren't taking direction from Israel, Trump has outsourced our Middle Eastern policy to the Saudis. His first foreign trip was to Saudi Arabia, a bad choice
badly executed. He supported the Saudis against our ally Qatar, where we have a huge military base. He's doubled down in Yemen even as the magnitude of the catastrophe has become clear. He's now being dissed in Congress, which seems motivated to rebel over Yemen by the absurd lies the Saudis have induced him to tell us about Khashoggi.
Maybe Trump has read and thought deeply about all of this, then reached the strategic judgment that the wisest Middle Eastern policy is "Do whatever the Saudis want." Or maybe the corrupt unfit imbecile is doing the Saudis' bidding because they pay him a lot of money. Even though I happily concede a lot of your point, Trump is uniquely subject to criticism here.