Their support of AQ is common knowledge. It was
drastically cut back if not eliminated after 9/11.
9/11 scared the Saudis, they were fine supporting
semi-covert operations, but a direct attack on the US had
them worrying about their own hold on power in Saudi Arabia.
They saw such a quick military response from the US.
They realized that befriending militant radicals does have
consequences, and they ran away from it as fast as they could.