it sucks that your husband couldn't let go of that pettiness for the sake of his own grieving son, but he wouldn't have been harmed if you let the grudge die with him. it was unspeakably cruel to the son who is still alive, as wrong as he might have been in the first place.
What? Whether heaven or whatever exists or not has no bearing on how cruel it is. Are you trying to make the point that it wasn’t cruel for him to not say goodbye to his dad because they will meet again in heaven? Or am I totally misunderstanding you