I don't know - it is a logical thing to try now that I have seen one in half.
For the ABS to work, the coils have to pull (or push) those pistons to make the brakes modulate.
If the pistons are seized up due to lack of use, then spraying them with a penetrating oil of some sort is logical.
Only reservation I would have, is to make sure the spray used is compatible with the brake fluid, if any was to seek in that far.
Makes more sense to get out on a back road and hammer the brakes once a month now.
PK