Can you produce the definitive, robust and objective definition of "reasonable"?
Look at it another way, can you provide definitive, robust and objective evidence confirming the OP's original post is absolutely accurate in all details?
Before everyone jumps in with the 'kicking boots', I am not suggesting for one moment that I do not believe the OP's account, simply because I believe it is reasonable to accept it.
I also happen to believe that it is reasonable to accept that the RPI may genuinely have believed that there was something wrong with the ticket.
i) attention was drawn to the ticket because it was rejected by the barrier
ii) the RPI may have been mistaken about where he thought Hightown was located
iii) the RPI could have phrased his question much better
iv) the ticket holder's response could have been phrased better
v) it seems likely that the ticket holder's response simply strengthened the RPI's (ultimately mistaken), but reasonably held belief that there was something wrong with the ticket
Had iii), iv) and v) not occurred it is likely that it could have been settled very simply as
talldave suggested. That certainly doesn't detract from the fact that a bit more professionalism from the RPI was desirable and as someone else remarked, being deliberately obtuse isn't awfully helpful either.