If Github's ToS says that they have carte blanc to do whatever they want with FLOSS licensed code, including to relicense it, then either every single codebase

If Github's ToS says that they have carte blanc to do whatever they want with FLOSS licensed code, including to relicense it, then either every single codebase on github violates their ToS or their ToS violates every single license and therefore the law. A reasonable attempt under these circumstances would be to remove every single FLOSS licensed repository on github, so I'd argue no, they do not make a reasonable attempt to remove infringing code.