If they mutely oppose the coup, before it concludes, and the coup wins, then they might well not get the worst of it. They can also do a 180 after the fact - the coup will be too busy purging the AKP.

If they support the coup, this undermines their legitimacy, and in the likely case that Erdogan wins, they will immediately be purged, along with the coup planners. Of course, that can happen regardless.

There's an old Soviet joke about this - three men are in a cell, and try to figure out why they are there. It turns out that one criticized a minister, another praised that same minister, and the third is that minister.