Even if I agree with you that he is guilty of conspiracy, the sentence is bananas. Someone I went to high school literally killed 2 people and got a shorter prison sentence than this. If this is the law working, something is completely wrong. I can't fathom how any non-violent, effectively victimless offense, can warrant 2 decades in prison.
But I agree that the sentence is completely insane, as our most of our drug-related laws.
Think about it another way, though. Take the flight instructor analogy, and say the guy he's teaching to fly is going to buy a Cessna, pack a bunch of C4 into it, and crash it into a hospital. If the instructor has knowledge of this, is he not partially responsible if the guy follows through?
I guess I just don't think that disagreement with the sentence requires disagreement with the findings of fact or with his conviction.
The main reason I'm responding to a lot of comments is not to defend the drug war, but rather to combat an incorrect "slippery slope" argument that regularly comes up in HN discussions like this. Something like, "Person X was convicted of crime Y because of facts A, B, C, D, E and F." and then there's a number of comments that boil down to "They're saying that B is illegal! What's next?!?! I do B all the time! The government is out of control!"