Fun fact: The IRS will let you report millions in income, claimed for illegal activities. You can literally say, “I got this from cocaine smuggling ring”. They do not care, as their job is to make sure you pay taxes on your gains based on the law. Of course you do not have to specify what illegal activity it was. Again, as long as you pay tax on it fairly, it is not their job.
There could absolutely be a there that the IRS has not made hay over.
But then again. Maybe they did already make hay about it. Recall, an ongoing audit was claimed as the reason why Trump did not release the tax returns in the first place.
Tl;dr, you are misguided in this claim.