Not sure they "caved". A protest is never rigid, both sides constantly adapt to what the other side is doing. In many instances, the protest hasn't stopped, it has taken a John Olivier sanctioned new form. Or even more subtle forms that will be a lot harder for Reddit to track and fight.
A well-organized protest can last a very long time. And you don't need a lot of people to do real damage. As a French, I'm very familiar with protests and strikes and whatnot. To me, these mods are adapting extremely well to Reddit's threats. Reddit will exhaust itself fighting this protest. spez is a dumbass, as this completely avoidable protest will require Reddit to dedicate a lot of resources to quell it. For a dude so focused on profitability, such a waste of resources and money is a hilarious result.
Meta requesting NDAs to discuss P92 means literally nothing. I once signed a NDA with a prospect (not even a client), and the whole thing unraveled in a very nasty way when said prospect showed very little respect for my work. The fact Meta wants people to sign NDAs to discuss a not-yet-public project is no grand conspiracy to kill the Fediverse. It's literally just how companies work.
More generally, the discourse over Meta joining the Fediverse is beyond irrational. People are discussing rumors as if they were facts (is there any evidence that Meta has offered payments to Mastodon admins?). They hypothesize and catastrophize everything. What about facts and reasonable hypotheses?
I'm not trying to defend Meta here. I don't trust them, at all. But not trusting them, and inventing an alternative reality, are two completely different things.