Are gentiles allowed to attend a séance? If so, why are Jews not allowed?

Just as most of the 613 commandments are geared to Jews and don't obligate gentiles, so too the Torah obligates this more demanding standard of being "totally/wholeheartedly with God" (Devarim 18, 13), and not do séances or the like, while gentiles may. Surely, if a gentile wishes to voluntarily accept this higher standard, it would be admirable, but God demands this only of Jews, similar to what Kohanim have even higher demands, compared with regular Jews, who are called "Kohanim" relative to gentiles (Shemot 19, 6).