Federated means that any instance that is federated with them receives their content and can bee seen on that instance.
Defederated means they are not federated anymore, thus blocking both users and content.
It’s usually done to combat content you don’t want on your instance
I feel like that wouldn’t be within his criticism. The way I understood it, it was that he, and I agree, dislikes the i-frame dodging-centric design because it relies heavily on something invisible like the I-Frames.
If there was an animation, a flourish or some other visual marker it would help tremendously.