Is it normal that my friend doesn't want to acknowledge my brother?

So my (26m) brother (29m) is autistic. He doesn't function like normal people, I know that. It can be a little embarrassing to be in public with him because he is impulsive. I DO NOT want to emphasize this part too much because it was only twice that something happened. Once at a restaurant, my brother came back from the bathroom and he had shitted his pants, and he was panicking, and it became a ruckus. My friend was there and helped me to clean him up. The second incident was during a trip we took together. A couple of days into the trip, my friend (27m) made a joke about the incident at the restaurant. I didn't like it, but it wasn't that serious and I said nothing. I have known him for years, and I value his friendship a lot, and I don't want my brother to stand between us. Well, that trip, we were planning to go to a movie theater, but my brother wanted to go to the museum instead. I told him he had to go to the movie theater, and he didn't like that. He started to cry, and started screaming at me, saying that I don't like him and that he only wants to go to the museum. He eventually started hitting me, and my friend had to pull him off. My friend suggested that we go to the museum, and I reluctantly said yes. My brother had been calmed down. On the way to the museum, my friend didn't say anything to me, but I could tell the trip had been ruined. When we came home, he said that the trip would be incident free if I had left my brother at home, and I was like, I can't believe you're being so serious about this. I told him that it happens, and he just nodded and went home. We haven't really spoken since. I have tried to bring up the museum thing, and he has always dodged it. He doesn't ignore my brother, but it's like he doesn't want him there. Well, we have plans for Christmas, but he has asked me if my brother could stay at home. I am sad that it's like that because my brother likes my friend and he knows that my friend is a friend. I said no because I know that my brother will start to cry, and I don't want my brother to ruin Christmas.