It's funny how things we initially found attractive in a person we come to dislike. My guess is this man's "childish ways" were seen as youthful initially. If she disliked it she chose to (ignore) it then.
"There are only two ways to experience joy and peace of mind in relationships: we either get what we want or we learn to be happy with what we have."
This woman has to decide if things don't change; Is this a deal breaker for her?
The truth is no one gets married looking to have someone change them. Odds are 62 year old person is "comfortable" in their own skin.
If she still loves and appreciates her husband for all the traits she fell in love with him than it's possible for her to (choose) not to get involved with issues that deal with the son.
Trying to get someone other than ourselves to change is a often a frustrating experience. If she can't accept him the way he (is) it probably means she made a mistake in marrying him.
People don't get married to (change) each other. They get married because they are "in love" with a person the way they are!
If it's a "deal breaker" get out!
If it's not a "deal breaker" learn to do without.
Only she knows how big of a deal this is for her and her marriage.