Doesn't surprise me, but they don't really have a lot to go on. The hospital did tests and didn't find anything wrong. A one off event does not wave any flags...
It really might be just a faint. People always assume fainters just close their eyes and go limp, but a faint can look a lot like a seizure.
I used to faint a lot. Laypeople would always think it was a seizure, because I'm semi conscious and "fighting" because everything is black and I don't know which way up I am. But if I fainted in front of medical staff, they would say it's just a faint and were not concerned.
Initially I was diagnosed with epilepsy and medicated because people panicked and called ambulances and told medical staff that it was absolutely definitely a seizure - I was stiff and pulling faces.
I lost my driving licence, was prescribed medication and had horrible side effects for years, had regular blood tests, and cables glued to my head for EEGs, and prodded and poked and scrutinized and....eventually, after several years, neurologists decided it was just fainting after all.
I lost about 5 years of my life to a condition I didn't even have. I was too scared to drive for 10 years after they gave me back my licence, and I still worry about it.
You are right to be concerned, especially as he drives for a living, and he should definitely go to his GP and get blood tests e.g. diabetes and ask for a referral for an EEG. Get things ruled out. If he has another event then yes, film it.
I'm not sure of my point. Just that consequences of being wrong go both ways, I guess 🤷