I think the Feb 29 interview was just a routine "apply the pressure" to see if the admitted shooter cracks.
As far as Serino's recommendation to charge, I think he knew what he wrote was bogus, and that a grand jury would no bill. Serino might as well have justified the charge by saying Zimmerman broke the underpants gnome rule. I don;t think Serino thought this case would get to a courtroom. he thought it would get to a grand jury, and stop there.
Glad you posted this, you’ve answered my question!
Too bad they can’t just disclose all the dirty tricks behind the scenes.