Why? If you're competitive why should everyone else be as competitive as you are? In the NBA, it is disrespectful because the the team supporters bought tickets, merchandise etc. On the other hand, this is just a game and no one invested money in your team to see it win games.
He can do whatever he wants to his team, just as long as he doesn't do stuff like create dummy accounts and sell his players at overpriced prices. If you think tanking is a valid strategy then feel free to gut your team and try it out. Personally I'd love it if everyone in my league tanked and forfeited all their games to me.