AITA for telling a disabled man I'm not giving up my seat to him on the bus because I also have a disability.

I take the bus every day to go to work. I've been doing this for a few months. A few stops before mine there's usually a man in a wheelchair that gets on. He always finds a spot to park his wheelchair and then sits in the seat next to it and uses a walking stick to walk the rest of the way down the bus and sits in a seat. I've never seen him stay in his wheelchair. The last few weeks though he's started to stop at the "disabled" section of seats and ask whoever is sitting there to give up their seat. (It's like 4 seats with a little symbol on the floor) He's always emptying those seats out now if someone is sitting there. One day he called out a woman for sitting in a "handicapped accessible seat". I'm starting to feel bad taking the bus now.<br><br>For context, I have Crohn's disease. My stomach is always a mess and it hurts to move a lot. I have doctor's orders for not standing up at work (which sucks because it's a customer service job and I'm the only one sitting). While not in danger of needing surgery, I have minor medical issues for my age. <br><br>Today I was running a little late and some dude grabbed the last available seat. The disabled guy got on before my stop and I grabbed the first available seat, which happened to be in the handicapped section. He made his way down the bus and saw me, and he looked at me for a second, working his stick along the bar. Then he said "Oh, this seat is for handicapped people." I said "I know". He was taken aback for a second. I was expecting him to call me a shitty human being or something but instead he just said "are you handicapped?". So I said "I'm chronically ill." And he says "that doesn't count". I looked at him and said "I'm not giving up my seat. Just because you have a wheelchair doesn't mean you're more disabled than me". (Honestly I didn't mean to say that, I meant to say "just because you have a wheelchair doesn't mean you need a seat more than me", but this is what came out) He says "I can't walk. You lied about being handicapped. Shame on you". Then he moved a little further up the bus and sat in a seat. I feel bad, but I also didn't think I did anything wrong. And I feel like a terrible person because I'm so irritated with him that I said that fucked up comment. AITA?