But Donny Dearest doesn't like Cali

Assuming it was actually Iran doing it, I think you'd have to assume it would be about logistics: perhaps that's the easiest dense civilian target for them to hit since the path east from Iran has fewer U.S. allies to intercept the drone. Though if you can hit the coast, going after targets in the PNW could cause more damage to the U.S. military.

If the Trump administration does this as a false flag, California could be a good target to garner support for the war.