So, after a Google search, it looks like the move is banned by many police forces because it is dangerous, but not in Minnesota. Minnesota training does acknowledge that it is dangerous that it should only be used while someone is resisting. After that, they need to be put into the recovery position. Something Chauvin never did, so he can't really say he was following his training either. He was following what he wanted to follow.
Officer Lane did in fact suggest to Chavin that they turn him over, and Chauvin refused.
https://www.ctvnews.ca/world/the-mov...-why-1.4960025
https://www.ctvnews.ca/world/the-mov...-why-1.4960025