If the Zoysia is mowed to 1" or less, the ball will not settle into it. It is a dense, upright grass with a rigid blade. If the ball doesn't roll into the bunker, perhaps the grade around the bunker should be looked at. Does it fall into the bunker? Rise up to it? Or is the area generally flat. In most instances where an action like this is taken in response to an adverse condition, one should first try to mitigate the root cause for the condition rather than just band-aide over it. Sand tends to blow (and be hit) out of bunkers and build up over time. It is not uncommon to find to find anywhere from several inches to a foot or more of sand (see the greenside of the bunkers at PB). This leads to a daughty environment that leads to turf decline (a major reason why supers "edge" bunkers into shapes different than what the architect intended).
Check the side oppositeof the prevailing wind and also the direction to the green to ascertain the degree of sand build up. Also, check the depth of sand in the bunker. If sand is just added year in and year out, the depth of the bunker can get shallower. The shallower the bunker, the easier it is for sand to leave it.