These are good questions and my apologies we didn't make this more clear. The GNU Social Contract is important because it defines what the GNU project stands for. It is a mission statement.
This is not true, the non-GNU anti-social edict doesn't define anything what the GNU project stands for, seeing that it isn't a GNU document to begin with. What the GNU project stands for can be read at www.gnu.org, or more to the point https://www.gnu.org/gnu/gnu-structure.htm Get it while it is still hot!