Earlier quoted context omitted.
This may have qualified as entrapment which could be why he was not brought up on charges for this. Still, IMO it is reasonable to bring that up as a character issue.
How would that be entrapment? The police have to remove your ability to make a choice for it to be entrapment. http://thecriminallawyer.tumblr.com/post/19810672629/12-i-wa...
Basically, if the undercover cop suggests X and you say no. Then come on nobody will know, and you say no. And then they spend the next six weeks convincing you it's a good idea, then that's entrapment.
The issue is he was on a sting for over a year and that's plenty of time to cross the line.
Of note, asking several times and catching someone at a moment of weakness is not entrapment. So, if you have been clean for 10 years then you’re out of luck.