I think
may well be more about being into sports than
, at least violent sports. The problem is that
dominant types also have strong
and vice-versa.
I think that what makes Commodus more likely
than
is precisely that he did not feel motivated to actively exercise his power over others; one gets the impression that self-indulgence in terms of having a good time was his chief motivation.
It is illuminating to compare Commodus to other tyrannical emperors such as Caligula and Caracalla, who were likely ESTp. They also liked to have a good time and were sports-mad; but unlike Commodus, they were active in (mis)ruling the empire and in trying to expand it, as FDG mentioned.
Commodus is different from another ISTp emperor, Tiberius, but it must be taken into account that Commodus became emperor at 19; Tiberius, at 55.