I don't think it's the NDA itself, so much as the tone of the way people framed their announcement of it.

Since I haven't used a Star Wars analogy in a long time, I'll try one:

If your babysitter wrote you and told you that they've got a meeting with the Galactic Empire to take care of younglings on Coruscant, but they can't talk to you about it, you'd probably be a little concerned.

Like you know how that ended LAST time, and don't really have any reason to think that this is somehow different, so you're probably going to freak out about it.

As with most things in life, if you make announcements, make them super vague, and include things like 'I'm going to talk to Zuck about his new project, can't tell you anything' then you're leaving it up to the interpretation of the reader.

And so everyone is going to assume whatever based on their biases, and if there's a group of people who are MORE anti-Facebook biased than Fediverse users, I don't know who that would be.