It's sometimes very hard to change the license of an open source project. Technically you would need to contact all of the contributors to the project (and there may be a lot of them) and acquire their permission.

In any case, RIAA already has a license to use the existing software. That license can't be unilaterally withdrawn, unless RIAA violates terms of the license that invalidates it. New versions of the software can be released with the new license, but RIAA can continue to use the older version with the original license.

And, as other people have pointed out, this would create a software license that is "non-free", and therefore incompatible with other open-source licenses, causing all sorts of headaches with software distributions, and any other software that has a dependency on the software.