I agree. Even though I don't think they should reprimand players for it, what option do they have? As an industry, it's kind of hard to sell yourself as a role model when you turn a blind eye to illegal behavior. I don't think it should be illegal, but it still is illegal at the Federal level.
Their only options are to either wait for Federal law to change, or to stop testing for it. While they might be able to get by with excluding THC from their drug testing program, I don't think the owners as a whole want to risk the PR storm that could potentially follow. It would likely be easier for owners in states that have legalized weed to get on board, but it's undoubtedly easiest for Jerry Jones. He has a $350M buffer to work with before he falls to #2 highest earning NFL team. I can't imagine there's a large enough portion of NFL owners who are willing to risk income on behalf of a small percentage of players who can't pass a single test.