Surely a smaller flush wouldnt fold?
It would take a donkey to not bet a smaller flush on the turn. Checking isn't necessarily bad if you have the nut flush or second nut flush. Not betting a small flush against bigger on spade hands is a huge mistake though. There is an inconsistency here in that if we were up against a donkey we would bet the turn because he would rarely fold. We don't have a need to balance a turn checking back range.
The inconsistency is only a donkey calls with worse but we shouldn't be in this spot vs a donk since we would have bet the turn.