Sutton foolishly went out on a limb for the sake of the drug trafficker and Aldrete-Davila rewards him by kicking him in the teeth. Sutton now attempts to cover for him because it's the U.S. Attorney's reputation and credibility that are on the line. Sutton had to save face. It also undermines Aldrete-Davila's credibility and integrity in court.
This kind of thing has happened numerous times throughout history. Prosecutors grant some lowlife immunity from prosecution for a crime. Then the lowlife goes out and commits the crime again. Prosecutors then extend the immunity to cover the subsequent transgression in order justify the mistake of giving him immunity in the first place and to salvage his credibility as a witness.
OK. Let me understand the conspiracy. Sutton grants immunity to a drug dealer (fact). Then that drug dealer, now known to the world of BP agents as he's testifying against two of them, SMUGGLES DRUGS AGAIN. He is caught by other border agents. They turn him in. Sutton finds out, realises he'll look silly, so he extends immunity for absolutely NOTHING in return. He expunges the record, purges the arrest report, hides the agreement, and gets the arresting officer, the court, and the jail personnel to go along with it.
Thus, there is NO EVIDENCE AT ALL that the guy was arrested again, as a result of a high-level government conspiracy.
Except that some average-joe internet poster named Cyropaedia knows all about it.
When an argument gets to the "of course it's true, but there's obviously no evidence because he hid it all", there's little more to be said.