Yes. This. We have so much invested in SourceForge including scripts, a whole Wiki and tons of history. Ideally we'd move to GitHub one day, but it'll be a sizable project. There is already a mirror of the code on https://github.com/kichik/nsis and hopefully more will come in the future.

As for SourceForge injecting adware, they only do that to dead projects or projects that volunteer. NSIS is neither. Many people approached me asking to bundle their stuff, even outside of the recent SourceForge efforts, and they were always swiftly rejected.