Caledonian, interesting. The SEP article on behaviorism seemed to be identifying "radical behaviorism" with the denial of the mental, but perhaps I misinterpreted? In any case I'm inclined to trust Wikipedia here, which indicates that the extreme version of behaviorism should be identified with John B. Watson, an earlier founder.

I do not, however, see any indication that the denial-of-mind version of behaviorism is straw; as far as I can make out, it was seriously advocated.