The equity isn't standard and it is odd. Only you can make this call. But if nothing else it seems odd.
One point, 98% of all business are not managed or dealt with as a startup like SV would. I have been apart of a lot of businesses outside of SV and so many were not structured as you'd expect based on reading tech blogs etc, but a few were super lucrative for me. SV is an echo chamber, don't use it as your only source of reality as it is really an isolated odd case of reality.
I'm the main developer of the extension. We use the public post to connect your Facebook profile with your user in our database. If you want you can just publish the public key without anything else. After we validate your key, you can remove the post.
If you have any suggestion on how to improve feel free to open an issue: