The only real fact you cited isn't actually any sort of advantage for sourceforge over GH [1]. I don't think sourceforge has an open backend or any iota of accountability given their history of injecting malware.

And I have no problem with a project not wanting to use github for this reason either - everyone is free to roll their own, or use something else, but the point stands that SF isn't exactly a better alternative for those reasons and most small projects should just end up on github because that's where a lot of OSS development has coalesced anyway and at least github has a been a decent steward providing free OSS project hosting.

1. "and the fact that GitHub is a closed source backend under control of a corporation that's accountable to no one"