Michael Flynn's company was caught red-handed for violating a number of federal statutes. The kickbacks he sent to Alptekin as part of the scheme are undeniable proof of the fraud Flynn Intel Group was engaged in. And he was paid by Turkey to be a secret agent on their behalf.
Trump’s DOJ's position is that the DOJ acted wrongfully by conducting a counterintelligence investigation into why Flynn was going around lying (to the Vice President, no less!) about the secret promises he'd made to the Russian ambassador.
Trump's National Security Advisor was an undisclosed agent for a foreign power, who was secretly paid millions of dollars to advance a foreign power's interest. There is no dispute about this fact. And Trump's DOJ now says it was wrong for the DOJ to ever investigate him for it.
Having a National Security Advisor who exposed himself to criminal liability while acting on the Turkish government's behalf, and then goes around lying to the VP about his promises to other foreign leaders, isn't just a law enforcement matter. It's a national security nightmare.
But some people are thrilled that he gets away with all that because reasons.