Yes, it is ulta passive and that's what makes it hard to play against. Every time you make one of those 10 setup moves, White has to make a move as well, and can easily go wrong and weaken his formation.
Once you have built the Hippo, that's when the game begins.
Instead of attack - attack - attack; it's prepare - prepare - prepare to attack - attack - attack.
A very different way to play chess.
Possibly, but the opponent gets to watch the hippo set up EIGHT standard attacks all of which launch on move 11. Sort of like watching a balloon slowly become overfilled and knowing its going to pop, which is different from watching a turtle shell STAY a turtle shell!
When your Hippo is built there is no rule that says you have to start playing aggressively like Nakamura. Just continue with passive play watching for weaknesses in White's formation.
Have a look at this 2010 Hippo of Tiger Hillarp Persson
https://www.chess.com/clubs/forum/view/128-steil-antoni-vs-hillarp-persson-1
I'm relatively new to the Hippo, but the fact that it involves about 10 moves of preliminary setup without any sort of attack in general, makes it feel passive to me. I'm still getting used to obviously, but it's certainly a different "animal" (pun intended) than most other standard, more aggressive/active openings. It seems like part of the strategy is really to invite the opponent to wast tempi and overextend themselves, while not knowing how to attack your solid structure.