Not defending Joyce, but where do you get that Folau isn't allowed to hold certain (idiotic) views? The issue is that he is paid big money to play and keep himself nice so not to put the game or his sponsors into disrepute. Not too hard, is it?
For as long as he wears a sponsor's logo he should keep his religious mumbo-jumbo to himself just out of sheer courtesy if nothing else.
My comments apply to this one instance only.