That's not how it works. This would fall under the Personal Conduct Policy. PCP violations involving drugs can enter the player into the Substance Abuse Program (Bell's arrest/DUI did) but once in the Program it won't advance him like a positive (or missed) test would. That's why Gordon was tested right when he got off the plane after the alcohol pic he posted. If he's suspended it would be under the Personal Conduct Policy.
Also, once a player is in the SA Program, for marijuana violations there is a series of fines before the player is suspended - 2 game fine, 4 game fine, then 4 game suspension. So unless there are other violations we don't know about (which there could be, the league doesn't disclose those fines) he may not be suspended for a Policy violation.