It's not that I didn't believe what Brian, Javi or Yuzu said. But in my mind, I'd imagine there'd be a time when Javi would just look back and asked himself did he made a mistake in allowing Yuzu to train under Brian? but since it's already too late, he can't take back what he said, so all he can do is to let it go and just try his best and be friends with Yuzu.
True that we'll never know what would happen if Yuzu stayed in Japan or train under some other coach. But as I wanted Yuzu to stay at the top, then I wouldn't want him to take any risk regarding his competitors. If he's really cunning (as I'd like to think he is, cunning in the inside soft outside) then I would assume he'd say no if ever Brian bring this topic to him. When Yuzu went to Toronto, Javi was considered a step above him, that's why it was to Yuzu's advantage that he went to train with Javi. Now, Yuzu is the one at the top, he should be more aware of keeping that spot for himself. I hope I make sense.