The mission of the Internet Archive should not be "copyright reform" but maintaining the continued availability of data it is legally allowed to host.

Then which organization is better positioned and able to push for copyright reform in your opinion?

That would entirely mean what you mean by "copyright reform". If you mean the typical crypto anarchist data hoarder everything should be free and open after 5 minutes sense, or anything close to it, frankly I don't support, so my answer is to route such ideas to /dev/null.