"Firstly, I believe the "anti foul" comment referred to not being able to coat the INSIDE of the suction strainer against marine growth - which IS a concern, not frozen fasteners."
Two sides of the same coin. It is EASY to gob antifouling paint
inside the fitting, but in order to paint
it, as well as to clean out the little critters that don't care how well you painted it, it is still necessary to unscrew the strainer plate, at least during annual haul.
And you will not be able to unscrew it, certainly not with a slotted screwdriver while in the water, unless you've used neverseize. Or impact tools and the risk of collateral damage.
that would really be a place to have flush mounted dzus fittings instead of screws, if dzus fittings came in flush mounts.