I have had a lot of similar experiences with air and train seat idiots.
My favourite train seat experience is getting on a train at London KX, finding my seat and sitting down, nice and early. I had reserved a seat as it is mandatory for the online advance purchase I made.
A youngish guy gets on my (almost empty, hardly any reserved seats) carriage, comes up to me and tells me "Move. You're in my seat". Very terse and very rude.
I'm , "Um. no, I'm in my reserved seat What seat number is on your ticket?" trying to defuse his stroppy attitude.
He refuses to answer, demands again that I move and when I refuse insists I show him my ticket. I decline to move or show him my ticket until he at the very least checks his own ticket.
He rants and raves a bit more, looming over me, and the train guard arrives and asks what is going on. Guard insists he shows his ticket and of course Captain Numpty has a seat reserved elsewhere, in fact just across the aisle from me. He grudgingly sits in it, no apology whatsoever for his aggression and rudeness.
Train starts to fill up and I overhear Gobby ask another passenger does the train go to a certain town. Reassured by the yes answer, Gobby goes to sleep.
Of course we get to his destination and Gobby is still in dreamland. I guess the poor dear wore himself out with all the unnecessary yelling earlier. I wait until the train is gently pulling out of the station to deposit my empty coffee cup in the bin behind Gobby's seat with a loud clang. Perfect timing for Gobby to open his eyes and see the platform signs receding into the distance. He gets rather agitated when he finds out he has a good hour delay now he has to get a train back from the next stop. I of course was all innocent face but dying of laughter inside.