Because someone else will do it for them. Saudi Arabia, Egypt and everyone based on Djibouti have a joint interest in keeping the Bab al-Mandab strait traversable.
It’s difficult to blame Riyadh exclusively without taking into account Iran’s role in the Houthis’ takeover of Yemen [1]. Saudi Arabia regionalised and intensified the conflict, but they didn’t start it. (To your credit, I don’t think the Houthis would have long-range precision weapons were Riyadh out of the picture.)
https://en.wikipedia.org/wiki/Saudi-led_intervention_in_the_...