For example, let's assume the entire current terrain is an 'Out of map' tile, and a 'Foundation' tile is placed on top of it. This Foundation tile is not an extra tile layered on top of another. Therefore, if it is deconstructed, it's equivalent to the tile itself being completely deleted. The old version of the Deployer did not have this issue, even with forced deconstruction.
If this is allowed, there is a risk that players will arbitrarily change the planet's planned terrain.