If you want pot legalized, then do something to fight for its legalization through the legislature. Continuing to break the law isn't going to change it, especially when it's not a violent crime (we don't have mobsters like Al Capone fighting to control the distribution of illegal weed, unlike what we had when alcohol was illegal).
Is it actually a big deal, in the grand scheme of things? No. But that's not the point here. He knew it was illegal, and did it anyway. Stupid.
Also, cocaine and meth aren't performance-enhancers. So would it be okay for him to have that, if he weren't dealing it or hurting anyone else? Flawed logic there.