If you consider 17 an adult and that the report is correctly identifying those games. This is no different than cheating in a video game online. It’s playing random people from matchmaking for rating points tied to that game. Maybe there were multiple tournaments as well for small prizes (probably under $1000 prize money) if the report on the report is correct though. I’d compare it to an NBA player cheating in a pick up game of basketball.
His past cheating AND the statistical anomalies related to his fast progress may also be explained by cheating in an Occam’s Razor sort of way is what is raising the flags.
I don’t care one way or the other, but I’d assume the worst.
He's still a child. He cheated when he was 16 (now we have evidence that he cheated at 17 too), and he's only 19. I don't think a 5 year ban (or honestly, even a 10 year ban) is all that extreme.