Why doesn't the article write about the actual threat to the fediverse? Embrace extend extinguish is such a common tactic it's hard to imagine this isn't what Facebook is doing.
Meta is that annoying little sibling that wants to be a part of everything when nobody wants them around. Except instead of a sibling, it's more of a disease.
A simple solution would be to ask Meta to opensource Facebook, WhatApp, Instagram and whatever their federated instance would be called code and in return, they can federate with the fediverse. I think that will show their true intentions on how much love they have for the opensource community. Put the ball in their court and if they agree, they will be welcomed to the fediverse as good faith actors.
I think fighting this will be a mistake. Instances ran by the likes of Tumblr and Meta can only bring more people into the fediverse, and when they're in it will be easier for them to move around.
The great thing about AcitivityPub is it lets the people who want to be in larger more centralised servers connect to those who don't fairly seamlessly.
Basically the sequence of events as claimed by the author is that:
XMPP small niche, small circles
Google launches Talk that was XMPP compatible
Millions joined Talk that could coop XMPP in theory
The coop worked only sparingly and was unidirectional, i.e. Talk to XMPP ✅ but XMPP to Talk ❌
Talk sucked up existing XMPP users as it was obviously a better option (bandwagon effect + unidirectional "compatibility" with XMPP)
Talk defederated
This demonstrated exactly the importance of reciprocity. If Meta plays dirty, defederate them then. Now is just too premature. Also frankly it is Meta that has more to lose than the fediverse at this moment as the bulk of users and thus the content are with Meta.