He was not punished for anything movement related
You're missing the point, multiple players having a high kill count and not ever having been banned means it is not as inaccurate as some make it seem, whilst being banned and having a high kill count can easily correlate to cheating due to this fact and vice versa. This does not rule out potential false bans, but it is a way to gauge accuracy and how well it functions, since players with more playtime/kills should theoretically get banned a lot if the anti-cheat is very inaccurate. Basically, if 99 players with 10k kills have not ever been banned, but 1 player out of that bunch happens to get banned then you could say 1 player out of every 10k kills could potentially be false banned, e.g 99% accurate over that time period. The accuracy would be determined based on playtime + false ban rate, however if it were possible to determine whether or not every ban was false then there would be no false ban situations, but this is an impossibility. As a sidenote, video proof does not really equate to much in todays standard for how far cheating has gone, most of the time it just incriminates the player more unless it's reproducible.