Ignorance of the law isn't a defense, even if it was plausible.
In order to be guilty of a crime the prosecution must show that the defendant intended to commit the crime he is accused of. For example if someone were to steal a pair of jeans from a clothing store, the DA must not only prove that the defendant not only stole the jeans but also intended to take the jeans without paying for them (a defense would be that the clerk did not properly ring up the jeans and put them in his bag).
That's entirely not true. Ignorance not being a defense is such a bedrock legal principle it even has one of those fancy Latin maxims:
Ignorantia legis neminem excusat.
You are talking about a specific intent crime. In this case, the specific intent is to take the jeans without paying and, additionally, that the intent was to deprive the owner of them permanently, i.e. the codification of the old common law offense of petty larceny. "I didn't know shoplifting was illegal" isn't a defense. Just as "I didn't know dealing drugs was illegal" wouldn't be.
Additionally if someone does not know that something is a crime they may receive a somewhat lighter sentence once they are found guilty
That's an entirely different issue from whether it is a defense in the first place. Guilt is one thing, sentence another.
In this case, though, it is completely implausible considering his public statements that Defcon was not entirely aware that there is this "drug war" thing going on and that it is highly illegal to deal in large quantities of drugs. Considering he was denouncing the very legal scheme he was violating, he was not only aware it was illegal, it was actually his intent to violate it and to thwart the drug war entirely.
Whether or not one agrees with him in principle on that issue, that's going to be very bad at sentencing.
