I support free software, but that doesn't mean dangerous offensive software shouldn't be regulated...

A currently viable virus should not be able to distributed freely without any regulation, even when it is licensed under GPL; the fact that viruses can be used for defensive purposes (hacking a hacker's laptop to get ransomware pass code, or hacking scammers to warn victims etc.) also won't change that.

It is the same way with lethal poison, just because it can be used in defensive ways, doesn't mean it should not be controlled.