“Exotic species are generally nasty, primarily because nothing eats them. They cause a lot more extinctions than people do directly.”
I take it you think E.O. Wilson was a fraud. His estimate was that 600 species have been extirpated in the US because of exotics. Even if he were wildly wrong it would refute what he said.
I have a more direct way of explaining this from my own personal experience. Environmentalists are abetting a mass extinction event, sight unseen and particularly among insects.