That seems a little extreme. I would maybe agree if 1) it wasn’t being made by the guy who has already got an AGPL project in Pixelfed and 2) it was on open signups. Whilst software is invite-only or closed entirely I don’t really see a problem in it not being open-sourced.
I get that, its basically just going back to the model we had before with Teamspeak/Mumble/Ventrilo where the image is meant to be specifically about Federated alternatives/