Good spiritualists don't have AI rebellions because good spiritualists don't have AI in the first place. You're confusing them for Xeophobes.
The fact that xenophobes can't do AI is dumb, it's like if Nazi Germany decided Tanks were abominations and put them in death camps, I'd love to know whose bright idea that was. Xenophobes should be proud of their accomplishments not building a robot and immediately calling it Xeno Scum. You built the finest robots from the best factories designed by the greatest scientists from the greatest people that ever existed, why are these bots Xeno Scum and not proof of their own superiority.
Having robots in general is a minor -5 penalty for spiritualists, the lowest faction opinion penalty possible. But not forbidding AI is itself a -10, and having Synths is a -20. At this point your faction dis-approval eclipses all gains you can have without going Psionic Ascension. If you are engaging with AI research as a Spiritualist, you are fundamentally not pursuing a Spiritualist ethic-based run strategy that would be using the strengths of the Spiritualist ethics faction (high ethics attraction and ease of making faction happy). You have no synergy reason to pursue Synthetics- it reduces your empire's happiness, stability, and influence.
Good, don't pursue these 2 valuable technologies, you are gimping yourself, and if you wanted to Gene Ascend your out of luck because your stuck with inferior computers. BTW you also can't turn on auto research ever because it will research the forbidden technologies. Through all of that though I'd be OK with it if literally one other ethic (not the bull with xenophobes) had the same kind of setup. If Materialist couldn't research Psionic Theory, Jump Drives, or Dark Matter without Starting a Psionic rebellion, Fine everybody has technologies that they can't develop without risk, it's fine that Spiritualist have issues with AI techs because they aren't being singled out.
But AI is a pre-requisite for a Synthetic rebellion. Ergo, to have the pre-requisite for an AI rebellion, you must already be not pursuing a Spiritualist build. You can not run into the problem unless you are playing anti-synergetically with the Spiritualist mechanics.
Again no other ethic logically has that restriction.
Synthetic Rebellions are far more of a mechanical punishment for Xenophobe empires, because having citizen-AI needed to avoid the rebellion is itself what degrades the ethics attraction of a Xenophobe empire. Xenophile- one of the strongest ethics attractions in the game- is based around having free non-slave alien species in your empire. Synths count. The only way to retain your Xenophobe ethical majority is to not have free Synths.
Which is still extra dumb because it bans xenophobes from using pop assembly entirely as they have just as many issues with genetic modification and cloning. Spiritualist can do gene Ascension no problem, they can even disable Synth Rebellions by just starting Synth Ascension.
This is where Synth Rebellions as a mechanical punishment actually punish a playstyle, because the Xenophobes who are trying to lean into the xenophobe faction will get burned for not giving full citizen rights.
Punishing a playstyle only makes sense if alternatives are equally available and other ethics can be punished for playing in not the right ways. Egalitarians aren't Punished for building precinct houses. Authoritarians aren't even rewarded for building precinct houses when enforcers should be the instrument for keeping your people in line, you can play Authoritarians just like Egalitarians without being punished.
If I'm supposed to play in specific ways to never cause a Synth rebellion then Synth Rebellions aren't adding anything interesting to the game might as well remove the Rebellions, allow players to play the way we want, and add cosmetics to Synthetic Dawn to compensate. Devs can always add Synth Rebellions back in with an internal politics DLC, because it would be an extention of a civil war system it would likely be much better.