He could be, you don’t know. Either way, a call to authority is a weak rebuttal. If you don’t know enough to counter his assertion head on then you likely know less than him. It may be Reddit, but a user who provides seemingly informed comments like the one in question on a sub-thread of this kind of study might actually have an informed opinion. Reddit is a large community and their are thousands of scientists involved in the research of cannabis at the moment, it’s a current hot-topic of discussion, after all.