I'm not stupid enough to assume that only hippies smoke up, but the casual users aren't the ones who are willing to move to an entirely different state, or change their voting habits, just to have access to legal weed.
Are there republicans who smoke? Sure.
But in the grand scheme of things, on a cultural and political level, they are fundamentally meaningless because they're not part of dominant weed culture.
In that regard, they're no different than the hardcore leftist who owns a gun and claims to get the 2nd Amendment, but continues to vote for Democrats because they like socialized healthcare or gay rights.
Sure they own a gun, but they're deluded if they think that makes them a part of gun culture.

