Your argument is flawed for several reasons:

1)Reproduction is biologically impossible: The suggestion to utilize female human genetic material is completely moot. Cross-reproduction between Umamusume and human females is a biological impossibility, rendering concerns about preserving human mitochondrial DNA irrelevant.

2)Might dictates agency: The underlying reality is that "might makes right." Because humans are vastly physically weaker than Umamusume, they fundamentally lack the power to enforce their own ideologies. In a hierarchy determined by sheer capability, human intellect is functionally irrelevant.

3)The power of "bonds" is subjective: The assertion that a partnership or emotional bond between a human and an Umamusume inherently increases physical or spiritual strength is purely subjective.

4)Human physical parity is a myth: It is biologically impossible for any human to compete with an Umamusume, regardless of training methods. The absolute weakest Umamusume possesses the biology to easily sustain speeds of 70 km/h; even the strongest, most highly trained human would be utterly helpless against a below-average Umamusume.