I get the feeling the FSF may have a thing or two to say about this. If it was possible to simply rescind the license from GPL code, there would have been sever

I get the feeling the FSF may have a thing or two to say about this. If it was possible to simply rescind the license from GPL code, there would have been several court cases that would have been muuuuuch shorter. Simply put, once the GPL license is applied, authors can only relicense future versions. Anyone can fork old versions and start their own development branch under a different name. The GPL also does not provide restrictions allowing authors to terminate the license for individuals while still maintaining the code as available as GPL.