You can't do a thing about this cheaters other than protest inyour own way. Send entire league an email stating that you will bench all your players and quit league if jackass doesn't play right. If not a positive reaction, do it. Have run in to it a few times over the years. Clowns all of them, don't waste your time, it is too valuable
Fantasy hockey only, not worth much in the grand scale of life.
Let him have his pathetic unethical moves.
Yahoo does not really get involved so it is upto you.
Bench entire roster and move on with your life, frustration isn't worth it.