Where are you seeing that he violated wildlife laws? All that's mentioned is a catch-and-release fishing violation that was dismissed - which can happen if the officer makes a mistake and it's found that no laws or rules were actually broken.
Edit: Not that it matters, but would also like to point out the following: I'm a person of colour and a supporter of Black Lives Matters. Finally, I didn't downvote you - though by all rights I probably should. Just remember - a person who is willing to call a black man a white supremacist has been been exposed here.
This is an old article, here's the follow up: https://www.nbcnews.com/news/asian-america/visa-reinstated-byu-student-japan-fishing-citation-speeding-tickets-rcna202216
TLDR; he got is visa back and is still in the US.