Something happened to me with my DS who has autism (and family) travelling to the long term car park at Dublin airport the other day.
We were first on the bus and I parked my DS's buggy in the bay for wheelchairs where flip down seats were situated. I sat beside him on the other flip down seat to be close to him as he can easily become distressed and had just been through a difficult 3.5 hrs flight. I have 4 slipped discs, DDD and an old coccyx fracture (which hasn't left me disabled but always in considerable pain) so the low flip down seat was a welcome relief. I noted the sign and decided I would (of course) get up and give up the seat I was on if I saw a wheelchair user or other disabled passenger get on. I didn't throughout the whole 10 minute journey.
A family got on at the next stop, grumpy man, a woman and two kids. I didn't see anyone else come through the doors beside us. He was hissing at his daughter and cracked jokes about messages on his phone (which only he found amusing). He turned away from me and whispered. I then heard him say something about 'not being able to read a sign'.
A number of people got off at the same stop including my family and his. It was then I saw an older woman with a crutch or walking stick going with him towards their car. It verified in my mind that he had been hissing about me in a nasty manner.
If I had seen the woman I would have offered her my seat. If they had asked me to let her sit down I would have had no problem. It was his nasty, judgmental, entitled, passive aggressive (which became just aggressive once off the bus) which pissed me off. I did enter into a short exchange with him saying "That was directed at me? You only had to ask, no need for that passive aggressive shit"(the only curse I used) to which he kept sneering "You need to learn to read." I didn't bother justifying our situation to him. My DS's disability and my own medical history is none of his concern.
I am only building my confidence in bringing my DS with ASD out since his diagnosis. This was obviously the type of crap an invisible disability can incur. I do not choose to sit far away from my other DC's when on buses etc but I had to watch out for my DS. My DH and other DS's were not beside us.
If I couldn't read, then I am sure I would be able to learn to, but I doubt him being able to unlearn being a prize one arsehole.
for your DS.