So far GGG hasn't fought anyone. He should do what fighters are supposed to do and fight everyone put in front of him. He is no super star. LOL. He hasn't even yet fought an A level opponent.
Fight him and keep the belt. It shouldn't be the most difficult fight ever and it's not like he has a big alternative fight worth dropping the belt for.
If Geale or another decent opponent isn't available for fighting GGG, then he should fight his mandatory and move on. Without that WBA title GGG would be even more unappealing as a fighter.