Now while we all no it wasn't the first time he did this, let me explain....
Conduct policy states that a "repeat offender" is defined by having committed an offense that brought forth league enforcement of punishment twice in a matter of 32 games.
Suh was in his 32nd game vs GB therefore he was operating on a "clean slate" not punishable by suspension.
That's the real reason he won the appeal. It wasn't legal.