Google/mozilla don't add legal language because legal language doesn't make something illegal. They can say "we'll remove your extension if we find out you've sold it", but they way they'd find out would be that the extension now serves malware anyway.
Although...I'm not necessarily opposed to that. Companies can change names and ownership a little too easily. Making it painful might help some things.
I personally think you’re on to something with tying companies to the reputation of specific natural persons, but I don’t think that is where we are going anytime soon.
This can be gotten around easily by making a separate Google account for the extension. It would require using gmail rather GSuite (without transferring over the entire GSuite domain.)