I see nothing wrong here. What would make me more upset would be a team that had no chance just dumping guys. That affects the balance of the league.
I don't see any difference between the first place or the last place team dumping Schaub (if that team had Schaub) here. What if he dropped Brees? Would most of the posters here if favor think it is still OK? What if he just drops Schaub, and doesn't even bother to pick anyone else up?
It's collusion disguised as a roster move. But you can easily see intent by comparing the dropped player to the other players of that position on his roster. and by looking at who was picked up in his place. If the guy dropped Schaub because he was his worst QB, and picked up a RB which he intended to start or possibly start in the future, I would have no problem with the move.
I'm not saying I would whine and threaten to quit the league. I'm just saying I wouldn't do it myself. If I was commissioner that owner would not be getting an invitation to play again next year. The reason there is no rule is because there can't be one. What's the rule supposed to say? "No owner can drop a good player for the sole purpose of letting another owner use said player."