@Simplelobsterhat
I think they've gone about this all wrong and of course you shouldn't exclude someone because of a disability. If they had concerns they should have talked to you about it and if there were ways of managing any potential problems, which of course there are. I'd be very hurt and probably not go.
However, I am wondering if something similar has happened before, as the concern is so specific, and someone has been upset/ scared without you realising.
I strongly don't agree with this idea that a girl should be less concerned about being pestered because someone obviously has downs syndrome. Yes she should be more understanding of why, but he's still an adult man so it doesn't make it any less potentially threatening when he doesn't take no for an answer easily, especially if it was a guest who didn't know him or the family and know you'd step in if needed. I know you said he would take no for an answer, and I'm not saying that is what happened or that it would be justification to leave him out, but I'm uncomfortable with the narrative from some posters that if a girl is uncomfortable with any kind of advances they are automatically prejudiced against disabled people.
Thank you. I've only read about 20 or 30 posts so far (don't know how many exactly as I view it on 100 posts setup, rather than 25), but I am very concerned at the
minimisation of women's concerns and fears I am seeing here. It is not 'ableist' or 'prejudiced' to have VALID concerns about a man's behaviour - and he is a man, any more than it is 'transphobic' to be concerned about men in women's spaces. I am sick of the #BeKind and women shouldn't state their fears. A man is a man, DS or not, if a woman feels uncomfortable in a man's presence, be he an able-bodied person and/or NT, or be he a man with a disability, the woman should
have the right to say so and not be silenced. Some of the dismissive posts I've read on here, dismissive of women's
genuine discomfort, have shocked and saddened me. I myself would no problem with a man with Down Syndrome at a wedding, unless he had been known to make women uncomfortable. But it seems the OP's son does make some women uncomfortable, this is quite clear with the sister/cousin not wanting him to be there. I feel the OP is in denial or has minimised his past behaviour, because it appears to be more serious than she is letting on.
Also, telling random women I love you is quite uncomfortable for women. If the OP can teach her son to ask for permission for hugs etc, surely she can teach him not to say I love you to women.
Bottom line is a person with DS shouldn't be infantilised and written off as not being able to learn, clearly OP's son can learn, and he has clearly made women feel uncomfortable in the past, and see seems in denial of how her son's behaviour affects other women. I suspect, by the minimising tone of the OP's posts the sister has tried to talk to OP about his behaviour before but she waves it away and doesn't listen. Bottom line is if a woman feels uncomfortable in ANY man's presence, she should be respected enough to be allowed to say it, and not invalidated, minimised, shot down or accused of being a bigot. A woman should never be made to feel bad for being uncomfortable.