Permanents with static battlefield replacement effects trigger during ETB

cards like [[Containment Priest]] and [[Corpsejack Menace]] have static replacement effects that only work once they are permanents on the battlefield. Currently, the engine processes these effects for other creatures entering at the same time if chosen before the other creatures.

For example, I cast a [[Last March of the Ents]] and choose Containment Priest followed by a few other creatures and they all get exiled. If i reverse the order, they all enter the battlefield.

The same happens with Corpsejack Menace and [[Purestrain Genestealer]]. Selecting Corpsejack Menace first causes the ETB counters to double, but the reverse does not.

The code I've found responsible for this is the isInUseableZone method. This gives a false positive for these abilities to apply while the permanent is entering. I was thinking of adding an additional check here to make sure the ability doesn't replacement effects if it's zone is Battlefield to prevent this, but want to make sure this isn't a deeper issue that should have a different solution.