If the stories are confirmed that AMLO threatened to drop all security cooperation with the US if it didn't drop the Cienfuegos case, then we have a case of the tail wagging to dog. But it gets worse

First, it meant that AMLO was willing to shoot his country in the foot to protect Cienfuegos. Cooperation with the US benefits Mexico more than it benefits the US -- we can and have kept criminal activity out of the USA fairly easily

Second, it meant that the US was unwilling to call AMLO's bluff. Assuming that we had the goods on Cienfuegos, then there was no reason to refrain from daring AMLO to follow though. But we didn't.

Third, it means either that the military has AMLO over a barrel or that AMLO himself is worried about dirt coming out in the trial. The latter seems unlikely, given how he has been willing to put EPN on trial (something that I'd bet a lot of money will not happen now)

To be clear, reason (1) is still bad even if reason (3) is true: it's hard to imagine that AMLO could not stand up to the military. He's choosing not to for reason we don't know, but that I will be willing to bet we will not condone when we inevitably find out

And reason (2) bothers me. Would an Obama administration have given in to an empty Mexican threat? I doubt it

There is only way that this ends well: AMLO puts Cienfuegos on trial, finds him guilty, and manages to keep him in prison. Good luck with that