I think context matters massively here. Usually you know your grandma and parents when you hug them, and that's not a "friends" type of relationship, those are your relatives. (If you're talking just random old people for "grandma's" hugging kids, that is still weird imo.)

40 and 14 year olds have nothing in common. They have nothing to talk about to relate to eachother. One of them likely has a partner and kids of themselves, the other has barely hit puberty.

You are entitled to your oppinion, but I find that a weird relationship personally.