If you really think a member is playing unfairly, you should use the report option on their profile, not post accusations in the forums.
https://support.chess.com/article/209-how-do-i-report-someone
That said, it doesn't look like that member is doing anything wrong.
The current CHAMPION league 1st player is cheating. He [removed -- MS] is spoiling the spirit of the leauge games of chess.com, he wantedly loosing games to stay low in rating so that he gets low rated players as opponents. Eventually, he can come first in the champion league by cheating like this and will get to legend leauge.