To me, it's that thing where people are free to interpret these scenes however they wish. Because those Uma Trainer/other Uma interactions were designed to give the viewers small spoons in passing, it can retain its loose implications for shipfuel. That's typical for even sports anime as a genre; as it does hold a reputation for having dedicated fan groups of yumes and fujos getting deluded in their own madness.
I personally never saw the implied "yuriful" scenes in the anime with Spe and Suzuka or Teio with McQueen as legitimate evidence. But those are the choices shippers tend to make nonetheless. In comparison, it's tiny to the plethora of Uma Trainer content throughout the stories in the game.
Especially if you know that the character career campaigns are the stories with the perfect trainer for each one. It's truly a wonder why that type of pairing is more popular than the other, at least in the circles I roam in.