The huge collection of modules on npm is one of the strongest factors node.js has going for it, so it makes sense for them to emphasize that they're not breaking compatibility with this in forking node.
They don't provide the Javascript runtime - Google does that. This is a fork of Node.js - glossing over this is at least a little disrespectful to Node.js.
There was a trademark issue between them and Joyent that also made the node-forward GH repo to go private. They might not be comfortable using term Node.JS on the frontpage.