90% of this is just driven by strong emotional reactions from someone that feels uncomfortable about people being open about their non-standard sexual life, in the same way that many people have weird negative reactions about polyamorous relationships in general.

The remaining 10% is just the author trying to sprinkle in cult-like insinuations to justify his contempt.

Regularly meeting with people that have shared interests and ideas is not a cult.

Finding some of those people attractive and having sex with them is not a cult.

But somehow the fact that the romantic/sexual relationships are not traditionally monogamous makes it a cult?