I think that I know the airfield in question (if not one very much like it).
The approach of refusing to move, that you are not on the runway because you are not on the marked bit is IMO completely legally correct, but . . .
(a) try explaining to St Peter (or whatever variant you have) that you shouldn't be meeting him because the law says the guy who landed on you shouldn't have done
(b) if it's a friendly place full of friendly people there's no harm in being friendly back, even if the guy landing might in your eyes be a complete muppet.
It's possible that for whatever reason the landing aircraft (which has right of way anyway) needed the wider area, he might have had a possible landing gear problem, it might have been a taildragger with the possibility of ground looping etc etc.
Its always worth remembering that there is always someone less knowledgeable and experienced than ourselves and if by acting the way you did you made it a safe and pleasant experience then where's the harm in that
