I don’t think the saudis would be passive if that happened, they would take it as provocation from both Houthi’s and their Iranian backers. The KSA has their own squadrons of F-15s for reasons. The only reason the KSA doesn’t act against the houthis now is that it would drag them into a war with Iran, but f the houthis attack Saudi Arabia first, that war is inevitable. Pretty sure Iran has already told them not to do it.