>>532673141
It's because his most famous horse, the "Hero" Deep Impact got caught doping. So he just wants to fucking bury the whole thing and knows Umamusume attention would just bring it all back into the public eye again. Just think of all the various horse trivia that gets posted here and imagine a Deep Impact story where she gets "supplements" from Agnes Tachyon.
He'd be (rightfully) humiliated all over again.