the truth might lie somewhere in between, i think its completely possible that the 190 offers "decent" turning performance even at low speeds. the d-9 exhibits surprising low speed stability and its completely possible that the rate margin is low enough as to be wholly overshadowed by piloting techniques and errors.
however, this is not to say that on a mathematical basis, the 190 would not inevitably lose out in an indefinitely long circle fight. it's just that in practice fights are much more dynamic than static str contests because you're always on some sort of timer and that will constantly skew the balance of the equation.
the phrase you're clinging to "offering turning battle" does not in any way offer an explanation as to why it does so. "at minimum speed" is a great caveat here; any aircraft driven down to the slow end of the doghouse can "offer turning battle" because it's on the wrong side of the e-m graph and has no other choice when pressured.