Which conceptually is absolutely ridiculous (and I don't see how it could stand up in court) because each player's original MLS club first waived the player, then refused to draft the player not once but twice. The only way the rights should be retained by the club is if there is a standing offer on the table for the player and the offer is for the the same amount of their last contract (which obviously isn't the case).
With the progress that has already been made via their collective bargaining agreements that could be be used as precedence, some of the current "rights to players contracts" could be ripe for challenge in the courts. Nobody wants to be "that guy" that brings the suit, but shenanigans like this are BS. A player that survives three rounds without being picked deserves to be a FA with zero strings attached. Granted, many of these guys still won't be signed, but trading a 4th round pick or $50K for their rights should not be an obstacle.