In Supersizing the Mind, (p. 88), Clark suggests that he thinks that it is a kind of "commonsense functionalism" that is supposed to extend. So, we might draw a distinction between a view (HEFC) which maintains that folk cognition extends from the brain into the body and world and a view (HESC) which maintains that scientific cognition extends from the brain into the body and world.
Then, one might say that it’s fine if there is extended folk cognition. That leaves cognitive psychology free to continue as before, studying intracranial cognition. Why should scientific cognitive psychology care any more about folk cognition than physicists care about folk physics?