There are no aliens as space does not exist. if space is not there then we cannot have aliens as are portrayed in the movies. I think you have a better chance of finding an alien like creature in the ocean vs believing in the vacuum of space.
Why do you say that space does not exist?
He is doing a play on words.
He is saying space is empty state of nothing so it does not exist.
He is not saying aliens do not exist on other planets in the universe.