Why Can Manny Ramirez Play in the Minor Leagues During His Suspension?

Forgive my ignorance on the matter, as I'm not well-versed in MLB rules and regulations, but why in the world is a suspended player allowed to play in the minor leagues before making their post-suspension major league debut? Now obviously I understand that it is in the rules that a suspended MLB player can play up to 10 games in the MiLB system, but still do not receive a paycheck of any kind. Paycheck or no paycheck, how can something like this be allowed? It's not as if the MiLB doesn't have a drug policy, because they do. In fact, it resembles the major league's system in every way. Well, except the part about being able to play at a lower level. If a player in the minor league system, let's say at the Triple-A level, gets suspended for the exact same thing for which Manny was suspended, said player is not allowed to play any games at the Double-A level. Which again begs the question, why does the MLB allow this? Why is it that major league players are not held to the same rules as that of ... (link)