Even though I may dislike this decision, it's within their purview to take on whatever advertising they want.
If they feel marijuana ads are not representative of what they do or who they are or what facade they present to the public, then that's their right and more power to them.
I do believe that if marijuana were made legal tomorrow we would see a slew of ads in every medium possible, that is, until the the government stepped in and told everyone what they can and can't say about the products they offer.