True, but what I'm saying is that this shouldn't happen in situations except for when a brand new creep is spawned, otherwise the person could just step on the site or kill the creep if the site's below another structure.
You can withdraw on the same tick yeah, but you can't use energy that you're withdrawing in the same tick, such as for building. You must wait until the next tick, simply because they game isn't sure the energy you're withdrawing will actually be withdrawn.