Concealing unconventional beliefs with high inferential distance to those you are speaking with makes sense. Dismissing those beliefs with the absurdity heuristic does not.

Also, I think you underestimate the utility of rhetorical strategies. For example, you could:
* Talk about these weird beliefs in a hypothetical, facetious manner (or claim you had been).
* Close the inferential difference gradually using the Socratic method.
* Introduce them to the belief indirectly. For example, you could link them to a more conventional LessWrong sequence post and let them investigate the others on their own.
* Ask them for help finding what is objectively and specifically wrong with the weird belief.