You're right, we don't know he is cooperating because we have seen NO evidence of it. Only evidence clearly to the contrary. So lets have the IRS provide us with the information of how he has cooperated with his tax crime. It appears a certain entity won't allow that to happen.
But again, you are trying combine the two when they have no reason to be. Hunter had a federal tax investigation. He intentionally tried to hide millions of dollars of income. and got caught. An average US citizen goes to prison for that. This isn't a case where a guy got mixed up and couldn't pay. Hunter could pay, he just chose to try to hide the income and that was likely to hide the source because it linked to his father's position as Vice President.
It appears as to the felony gun charge you are just falling back on the old "well he could have gotten a gun anyway" defense. So I assume you will no longer going forward have any comments on US gun laws. Ok. Regardless, the President of the US, the father of the accused, has stated that no American should have such a weapon and vowed to fight gun crime in America. And yet when his OWN son is caught...red handed, signed/sworn statement..... oddly, there are no charges.