Nothing. Just read Mozilla’s Manifesto

Your trolling skills are subpar but given this is a lazy weekend I guess I'll bite just for the entertaining value.

Let's go through "Principle 2, 3, 4 and 7", shall we?

Principle 2 The internet is a global public resource that must remain open and accessible.

Making source code available through GitHub is a realization of Principle 2. You got it exactly backwards.

Principle 3 The internet must enrich the lives of individual human beings.

I don't even know what could possess you to believe that making a software project available through GitHub would jeopardize this. Anyway.

Principle 7 Free and open source software promotes the development of the internet as a public resource.

That's what making FLOSS projects available to the public through GitHub does. GitHub, by providing managed hosting to Mozilla to host Firefox's project tree and making it available to the public, is unquestionably meeting this goal, both in its letter and its spirit.

You need to put some effort into finding things to be outraged about.