You might have seen this video (or something similar) featuring this guy going around. I’ll leave the final judgment up to each individual, but I’d like to provide some context and info about the person in question to the English speaking side.
He’s actually notoriously infamous among Japanese racing fans, not just because he cosplays as a jockey, but because he’s known to break rules: attempting to touch horses, entering the winner’s circle without being an owner or connection, or even pretending to be associated with a stable to access restricted areas.
In the end, he’s really just an attention seeker, so perhaps the best response is simply to ignore instead giving him the spotlight.
(It was kind of funny actually seeing some people mistake him for Ryusei Sakai and proudly post their “photo with Ryusei”...)