It is standard policy for the DEA not to participate in any forum where they believe their participation would extend legitimacy to said forum. In essence, they have already stated, loud and clear - your movement is illegitimate.

Somewhere it says, "The Controlled Substances Act of 1970 (CSA) was enacted to regulate the lawful use of, and eliminate the illegal distribution of controlled substances."

The end result is, "eliminating illegal distribution of controlled substances through elimination of distribution altogether by redefining lawful use as illegal distribution."

The movement is not won by flipping the DEA over, it is won by doing what you think is right - despite the reprisals of the DEA - in numbers sufficient to render the DEA of very little importance.