The 12 clubs might not have expected it, but there was a reason they launched this project without having their approval (or rejection) in the first place. The same goes for PSG, who might have had their own reasons for not approving. Still I think they were expecting these clubs' reluctance, but hoping to force their hands with FOMO. Them not joining sowed doubt, but ultimately they would have pushed on, as long as no one else jumped ship.
Honestly I'm most surprised by the lack of reaction in Spain and Italy, like you said they reacted spinelessly. Maybe the fans of Madrid and Barcelona think of their clubs as god's gift to mankind, but I really didn't expect this complete lack of solidarity towards their own league. I mean both countries are football mad, yet as far as I know there wasn't any wide spread protests at all. Really shines a bad light on their fan culture.
On another note, I seriously hope the rumours of UEFA bribing the PL 6 to rejoin them, are just that; rumours. It would be a huge middle finger to the rest of the league, as well as to the fans who stood up to the owners, if these owners get rewarded for being so greedy and out of touch with their supporters.