Google cannot take action against religions (even cults) it disagrees with (even for valid reasons for disagreeing with them), unless it gets over a very high bar of impacting business behavior.
The other path leads to far worse outcomes.
Morally, we cannot judge what happened here without hearing from both sides. But if action is to be taken, it should be taken by a prosecutor, not an employer.
"Disagreement" is quite an euphemistic way of describing the situation. The said cult has documented history of sexual abuse.
Google has standing for workplace sexual abuse. If I am a member of a religious / national / ethnic / etc. group with a track record of sexual abuse, I cannot be fired for that. That's discrimination.
There are many minefields here.
- I've seen many community members where I live boycott (unrelated) Russian businesses since Putin's invasion of Ukraine.
- I saw Muslims in the US persecuted after 9/11.
- I live in a Protestant/Atheist community which seems to hate Catholics.
- Etc.
Every large group has a bad component. There was sexual abuse in the Catholic church, 9/11 happened, the US did kill around a million Muslims in recent decades, and Russia shouldn't have invaded Ukraine. Laws are designed to protect individuals from generalization or stereotypes about from the group they're from, whether true or not.
Nepotism, for the most part, is legal in the US; it's just bad business beyond some scale. For a startup, the right strategy is often to hire people you know to be good personally. That's often friends and family. For a family business, the goals aren't purely economic, and again, it's fine practice. For large businesses, it tends to be bad business, but that doesn't make it illegal. Ditto for self-dealing.
There are restrictions for non-profits, public employees, etc. but those aren't general to private businesses like Google.