IMO, the substance itself isnt a huge issue, if anything marijuana would be a bigger deal. Hear me out.
The only difference in penalty is if a player test positive for roids its an automatic 4 game suspention. When it comes to weed a first time offender has to enter the substance abuse program and their name only becomes public if they fail a second time (and than a 4 game suspention). When a player takes roids he is using it to enhance performance on the feild, not using it recreational like marijuana users. IMO, this immediate embarassement would mean the player would be less likely to do it again.
When a player fails a weed test (especially one they know is coming) is way more irresposible. Its more about surrounding yourself with the wrong type of people. And chances are he will give in to peer pressure again, and again, and again.