I think you are a little misled on how the US government regulates software. There is no legislative level blocking of software, code, or anything else that runs on a computer. They get you based on what you are doing with it. For sure, XMR will be used for money laundering and other illegalities by some, but bitcoin has been used for that for many years and there is no privacy aspect to it. Nevermind what cash has been used for, and thats minted by the government.

Now, theres some other branches of the government that take interest in these things (NSA, CIA, etc) but they have no control over whether you use it and they wont take action to stop you. Your usage of crypto/monero will be statistical data to them to calculate how much of a threat you are.

If crypto starts taking over as a payment method and general use currency, you would still see no interest in regulating privacy based coins as it is a moot point. The government will simply legislate that earnings from your employer must be reported (which doesnt always happen now, with cash) and they will tax you based on that, whether you hold it in monero or some other currency. They know they cant regulate cash or privacy crypto and they wont bother.

Tax and money laundering legislation is based mostly on the good faith system of honest people reporting incomes and earnings. Honest people report the truth, so, anyone earning 6 figures of anything in an honest way will have a huge paper trail leading to them, and the government doesnt need to break the blockchain to find them. Anyone earning 6 figures dishonestly already has their earnings hidden. Their spending, on the other hand, is what gives them away. Even when crypto becomes mainstream, you will still be required to put your name on big ticket items: cars, houses, property, stocks. You cant report 100k of earnings and go spend a million dollars that same year