Just because KC Cap was "the only soldier that could match Superman move for move" doesn't mean he was equal to KC Superman.
Whereas Superman was stated to be stronger than ever thanks to continued solar absorption Cap was still the same Cap by all accounts. The fact that Superman took that many Shazams to the chest without going down and only suffering moderate damage is proof that he was >> to current Superman.
Superman was trying to reason with Cap while Cap was brainwashed and consequentially bloodlusted. If Superman had been bloodlusted the fight would have ended sooner in his favor.