Did you try it?
My understanding is that IndexFileDeleter will actually delegate to the configured IndexDeletionPolicy for the final decisions.

I can imagine that not all paths are "trapped" this way but still there would be some good value on the ones which are safe to postpone by Lucene's design. If we wanted to override/stretch the expectations from it, we could catch the specific invocations in the Directory implementation but that sounds like more tricky to get right.