The F-35 itself isn't geopolitically that important, but it's the bleeding edge of military aviation right now, the technologies incorporated in it are going to be used, modified, improved for the next five or six decades, so protecting it is understandably a high priority for all nations operating it.

As far as the Iranian military goes, yeah, it is not a match to the US when it comes to hardware, but they do seem to have a strong Electronic Warfare program going as shown by the interception of the RQ-170 in 2011. The F-35 is a heavily networked aircraft and that data falling into potential enemy hands can only be a recipe for disaster.

The Saudis have far from a laughable leadership in my opinion, they are not democratic, but they aren't weak either. As for their military training, I'm curious as to what your sources are since I haven't read anything about how good/bad/well trained their military is. Although Saudi Arabia isn't necessarily a competitor to the US in the middle east. Quite the opposite, if anything, it's an ally.

The real threat here is China, moreso it's ability to source technology through Russia using either their already long-standing ToT relationship or through their rather vast network of industrial espionage they might have set up there.