To avoid being charged for the more serious crimes he did commit.
Present the evidence to back this assertion.
I already did. You think that a retired 3 star general lobbying America policy makers to support another country without disclosing the fact that he was paid $500k by foreign interest is 'a manufactured process crime'.
Spendulus took a different route and pivoted to "he wasn't charged with the crime so I don't care stop talking about it" attitude.
I could also prove that when he eventually did file as a foreign agent, he made materially false statements and omitted information he was required to provide, but honestly I don't think there's literally anything that would convince either of you that Flynn committed serious crimes. Trump said he's innocent - in your minds that trumps any actual facts. Plus you could always just google a bunch of articles defending Flynn.
No, you really have not shown that he was guilty. I understand that you think you have, but you have not. You'd have to do quite a bit of research, and prepare a properly argued brief, to get half way where you think you already are. You'd have to cover the common arguments by defense in said brief. And defeat those arguments.
There are many technical details in such a matter, and there are numerous standards to be met before a DA would take a case and bring it to court. He'd have to be pretty certain that he was going to win, right?
In late 2016 he:
Registered as a lobbiest.
Did not register as a foreign agent.
Lobbied to support Turkey.
Was paid $500k by a Turkish company.
In March 2017 he:
Registered retroactively as a foreign agent because of his actions in late 2016.
What have I not proven. If we can agree that the above is true I'll move on to the false statements and omissions he made on is FARA filing.
Or, if you think it's not a big deal like TECSHARE I won't bother.