If you were to bail out of an airplace that was going to crash or explode and kill you. Do you think it would be legal for someone to shoot you while you float down to the ground?
If you believe it is, then please explain how so.
That's not how law works. It is not the case that all actions are presumed illegal and then explicitly made legal. On the contrary, all actions are presumed legal, and then certain actions are explicitly made illegal. So it's problematic to ask someone to prove or explain why something is legal. A much more reasonable way to go about it would be for the person asserting that something is illegal (i.e., you) to cite the relevant law that makes it illegal. You should be able to do that.