You are comparing someone saying that if you agree to work under certain rules that you should follow all of them to someone who supports corrupt laws and governments? The two are completely different.
Abiding by rules you agree to is not the same as abiding by laws passed by corrupt politicians and warmongers. One you willingly agreed to and the other is forced upon you. If you get hired at a job you agree to play by their rules. If you decide to protest those rules you end up not working.
Listen I am all for pot being legal. But my job drug tests. If I get stoned and they catch me I don't get to say that the rule was petty and corrupt. I get fired. Diaz isn't immoral for what he did. He's an idiot for doing something that was against his contract.
If my job started testing for pot I'd probably quit the next morning.
But I get 100% what you're saying. If you sign a contract with the UFC, you know what substances are allowed, and which ones aren't.
However, as much as I don't like Diaz, it's a weird situation that he's in. Pot is legal in California (where he lives) with a medical card (seriously, I wonder how hard those cards are to get though, everyone in Cali seems to have them???), and Diaz has a card. Where things get interesting is the UFC says you can't use it (and also the federal law which allows the feds to raid legal pot shops in California).
What gets me, is I don't in any way see how pot could be considered performance enhancing. I know some people say it makes them become ultra focused during a workout. The few times that I've been to the gym high I think I wandered around for about 45 minutes, and did 3 exercises. If someone wants to train high, I really couldn't care -- however I can see how it's a "role-model" / reputation thing for the UFC.