Earlier quoted context omitted.
Joffrey was a Clueless if ever there was one. He had no grasp of strategy, no skill at manipulation, no understanding of how to present himself. His mother on the other hand was a Sociopath's Sociopath.
I agree that he was clueless. He was also a sociopath and nominally in charge, though not by his own choice. A patsy set up to fail. And I 100% agree on Cersei.
Both abbreviate to “sociopath” but they are very different concepts.
I don’t think Joffrey qualifies as a GP Sociopath at all, as GP notes. While he was “in charge” he didn’t play the GP Sociopath game, and so was quickly removed. As the OP notes it’s possible for Clueless to be placed in positions of power in plenty of cases, for example when a fall guy is needed, or a puppet. So just wearing the crown doesn’t mean he MUST be a GP Sociopath.