Even if you think Saudi is an enemy of the US, the enemy of my enemy is my friend.
The house of Saud and it's people are mortal enemies with the regime in Tehran. And the regime in Tehran in infinitely more dangerous to the USA than the house of Saud ever has or will be.
The Saudis have been an invaluable ally to the US in the ME in countless ways over the last 100 years. We would do well to preserve our relationship with them, at least until time and/or revolution brings true democratic accountability to Tehran and Iran's threat to the US and our allies is greatly diminished.