He rather questions modus ponens? Things can have many causes, that is why the presence of the effect in absence of the cause does not mean there isn't a causal effect. Rain makes grass wet, even if the grass is wet without it having rained first, because there are presumably many reasons the grass can be wet (eg sprinklers), even if they are unknown to us. That having been said, this specimen is a hilarious face palm, all the same.