I don't think it has anything to do with the genre or content of his music (which is far from unique), but rather the fact that he's still technically serving a custodial sentence and apparently shot a video violating multiple public health and safety guidelines. I think it's legal for him to engage in commercial activity, but the federal government will probably take most of his profits until his sentence is complete.

https://www.nytimes.com/2018/02/17/books/curtis-dawkins-gray...