This will add a lot of inlined code and redo the filterByLocation that was already done in isFilteredSource/isFilteredSink. On the other hand we don't really want to expose those two predicates beyond the SourceSinkFiltering module, as they can be confused with isRelevantSource/isRelevantSink. So instead I'd suggest adding an inlined predicate to the SourceSinkFiltering module that performs this check.

      bindingset[source, sink]
      pragma[inline_late]
      predicate isRelevantSourceSinkPair(Node source, Node sink) {
        isFilteredSource(source) or
        isFilteredSink(sink)
      }

and change this like so:

(With this change, module AlertFiltering can remain private)

Thanks for the detailed advice! I updated the PR accordingly. PTAL.