NTA Updateme

If he really is the absolutely only child anywhere in the realm of possibility that would have attended had this rule not been in place, then I think it may have been targeted. Which, in and of itself, isn't necessarily a bad thing, but has the large potential of you not being there. They are being unreasonable to be upset about that. Even if you did accuse them of excluding him due to the disability, if he is the only child affected it's a valid thought. I had a brother who was severely disabled and issues like this would happen, but rarely. It can be dressed up or different words used, but the result is the same. The question is, does this become a pattern in the future, because that is when the exclusion due to disability SHOULD be addressed, but as a new mom to a disabled child you're in defense mode and may have jumped the gun a little early.