I heard that some pubs might not be allowed to show the match if it means that more people will be meeting in them. Don't know how they would enforce that, probably rely on trust and goodwill on the owners part.
It's not the manager's who decide if they play the youth. It's the owner and board.
No manger is going to risk playing a team with too much youth in it if the target is challenging titles and advancing in Europe. We've seen that for years.