One more point of view because I have reread the question and you may have meant something different . I was thinking you was talking one on one but your question seems to imply differently a 50 year old hanging out with a group of young people. If that is the case I would ask myself is he joining in the conversations , is he participating with the others or they with him , if yes then it’s up to the group. They must want his input.
If he is sitting by himself with no real connection with anyone else that may, and I say again may be a totally different matter
