I think it's undercounting or failing to consider the likelihood of natural causes. That is to say, physics, biology, higher-dimensional weirdness, etc, that we

I think it's undercounting or failing to consider the likelihood of natural causes. That is to say, physics, biology, higher-dimensional weirdness, etc, that we don't know of and can't anticipate, but is as natural as red sprite lightning. Planes chasing tic-tac aliens could be doing the high-tech equivalent of kittens chasing a laser pointer.