What law is that? I'm not familiar with such a law but can't imagine it would even be constitutional. Eg the law Jack Smith indicted trump with recently is about protecting federal/conditional rights.
Yes, the commerce clause is quite expansive and is interpreted expansively, but at the least this would be a first amendment issue and Congress can enforce that and does
That citation and the quoted bit limiting the law to interstate commerce is already in the first comment you replied to. I think you have misconstrued something.
The law we're all talking about prohibits a government employee from searching or seizing any product materials intended for use in production of communication materials that affect interstate commerce.