I will put it this way…
I was very glad to hear that my brother was assigned to the Presidential maint. Unit. The maintenance field of the military has been under assault for a very long time.
It would be plausible for the cabal to use multiple vectors to down aircraft. I am skeptical of a single point of failure - a simple EM weapon or 'hack' - but people of the caliber to notice such a vulnerability or react to it were pretty much driven out of the ranks by bad policies and other forms of fuckery.
It shouldn't be possible to hack a plane and bring it down. But… The F-16 was the test platform for a number of modern FBW systems and upgrades. The superhornets, F-35, and F-22 all use, effectively, cloned hardware and programming from the F-16s used to prototype the systems in the first place.
They even had F-16s rigged up to 'simulate' the flight characteristics of the F-22 at one point.
So, the code can be changed. Perhaps not remotely, but if you have people in place to insert vulnerabilities or to connect systems that should never be connected to open up vulnerabilities…
It becomes much more possible.