In general, entrapment is when the police convince you to commit a crime that you wouldn't have committed otherwise. So, if you want to kill your wife, and your friend (FBI agent) happens to say one day, "Hey, I do a little killing on the side, just for gits and shiggles," and you hire him, that's not entrapment.
In contrast, if the agent is manipulating you and saying, "Hey, your wife is going to divorce you and take your stuff. Killing her is the only way to prevent ruin" and slowly convincing you to do it, then that's entrapment.
Bottom line: Already predisposed to doing the crime and probably would have gone through with it if it hadn't been the police? You're screwed. In contrast, if you're normally completely innocent and the person has to convince you to commit the crime, it's entrapment.
I suspect it's more likely they wanted to convict him on just the SR charges because that's better publicity, but it’s still odd.