Isn't there a steelman custom on LW?

Yes, but there is a point where we should put our feet down.

I think Aumann's deeper point is about map/territory, and how we should treat modeling as more-tentative-than-currently-customary (almost everything is modeling, and since all models are false it is useful to hedge/diversify).

Even a very diverse map has to bother with object-level predictions that fit the object-level territory. Religion has so far been an utter failure at doing so.

Of course, one could charge that it's not intended to do so, and yack on about separate magisteria or compartmentalization, but in that case, bite the bullet and simply admit that words like "true" or "real", in their everyday sense of mapping a territory, do not apply to religion.