I am not confirming or denying the guy’s claims, but I can say this for sure:
If you can build a magnetron, you can build a directed energy weapon, and we were building them at that time.
It doesn’t even take anything as advanced as a klystron or magnetron to generate an EMP pulse, nor a nuclear reaction. A spark gap with a hefty capacitor bank, focused using a waveguide, and you have yourself a very simple directed energy weapon capable of disrupting modern unshielded microelectronics.
To deny that fact would be to discount the work of many great WW2 era scientists and engineers, not to mention just totally disregard most practical applications of high powered RF fields.
I am a middle aged engineer in the semiconductor industry, and I can guarantee you that the technology existed at the time to be able to disrupt what we consider contemporary microelectronics.
I would lean on the side of this not happening the way the guy said though, based on the fact that any sufficiently advanced alien technology base would have proper shielding in place to protect against such directed energy (and I don’t mean star trek/wars shields here, just faraday cages, and lead or foil shielding from cosmic ray particles). You couldn’t fly through space without it.
His claim was that the UFO was fired upon by a beam weapon from a plane....moreover there were no beam weapons at that time. Just because one has components does not a weapon make. I am older than you by twenty years (if you are middle aged). The things I have worked on (and continue to work on) have all been of the SDI variety. Klystrons do not a laser make. Magnetrons do not a directed energy weapon make. It is nice that you do semiconductors...all that equipment that you use to produce the devices is years in the making. The truth is knowing the fundamentals is NOT the same as producing a weapon.
EMP/HERF/Shock Pulse Generators
I don't think the classic saucers fly through interstellar space. They're more like scout shuttles to and from the mother ships like the ginormous ones over Hudson Valley, Phoenix and Stephenville.