The answer is "do you think he is going to continue the behavior?" If you shell out $10,000 to keep him out of prison (which may not work anyway) is he going to turn around and sell pot again. The answer is probably yes. Now if you get him out of it and he moves to a state where it's legal, then maybe you could consider it. However, the chances are good that he will get out and get caught again at which point you are out ten grand for nothing.
One of the people I discussed in the article was a friend of mine who took out loans to keep his son out of prison for the possession of Marijuana. The kid would get out and within months, he was back in jail. Nowadays most of these people have moved to California, Nevada, or Colorado. If you do decide to bail him out, I suggest he relocate.