by the definition of the word we are a cult, but since that term has evolved to have a negative meaning (mostly as satanic cults, referring more to the OCCULT) this may be used as an insult. So yeah even with the more modern meaning he's still wrong
If anything the furry fandom fits a better description of being a cult in the negative sense of the word. Not only because of the hiveminding but how they want to indoctrinate people into their deggeneraccy.