Please forgive me if this was already posted. In order for MG to put "organic" on their bag, they have to be certified by an agency that is acting on behalf of the US government. Below is an excerpt from the website for the National Sustainable Agriculture Information Service.

Over the years, it has become commonplace to understand and define organic agriculture as farming without synthetic pesticides and conventional fertilizers. This should not be considered a definition but a characteristic — only one characteristic of a socially and environmentally conscious approach to agriculture that is currently experiencing rapid growth in the U.S.

So growing weed in a container in organic potting soil does employ some ideas and methods taken from organic gardening, it does not necessarily make the weed "organic". Also MG makes an organic garden soil and an organic potting soil.