I agree that no system should work this way. Unfortunately most of the criminal justice system does work this way.
Cops going out to buy drugs to take down drug dealers. Cops going out and dressed up like prostitutes to take down Johns.
All of it is entrapment and all of it happens all across the US.
What if one or more of these is proven true?:
(a) the “crime” was Logan Act (not ever enforced)
(b) Flynn was never told he himself was being investigated, that the conversation was for background of something else
(c) they told him he didn’t need a lawyer present