They lied to him from the outset.
The FBI had no valid reason to interview Flynn in the first place because they had no evidence he broke the law.
Trump was going to expose all the hanky panky that had been going on.....remember the call to Ukraine that resulted in a bogus impeachment?
Flynn new where all the skeletons were buried, they had to get him at all costs.
Now you are getting into conspiracy theories.
Let's be clear what the call was about. The Call was about Flynn asking the Russians to not go apeshit about a new batch of sanctions Obama was preparing on the way out.
That actually IS a violation of the Logan Act.
Again, Flynn isn't some street punk who knocks over a 7-11. He should know better.