Yes, Charlotta, it is a difficult subject, but I think that a family that shows respect to all members can come up with a way around it - and it is those tips that Grans are so good at!
My own mother didn't want to kiss her grampy's tickly beard, and asked if she could kiss his bald head instead! We have one photo of the two of them together and I always remember the story when I see it!
Nowadays, we say, quite rightly that children should not be forced to kiss or hug someone they don't want to, but that is only part of the story, and working it out like that is what families do.
I have worked with families where disability is an issue, and usually they come up with phrases to help everyone get around it "my silly wobbly hands" etc. "Blowing kisses" (useful during chemotherapy etc.) is an old way of managing emotional closeness without physical proximity.
I do think though, that this little boy needs a proper explanation, and a bit of problem-solving about how to deal with GD. I wonder if everyone is expecting too much of themselves & maybe of a little boy. He will, in the future, be glad that time was taken to sort this hiccup out.
I cannot remember being forced (I'm sure I wasn't) to sit with the old people in my family, but I do remember sitting & listening for hours. I am so glad that I did, as I carry the memories of those who lived in very different times and whose experiences taught me a lot.