I don't think this really works. A PEP has to present a consistent
view of the world, and works as a cohesive whole. Arguments against a
PEP don't form a PEP in themselves, they don't need to be consistent
with each other; they merely oppose a particular set of propositions.
So an "anti-PEP" would not be anything like a PEP; it would just be a
list of assorted arguments.
I agree, and that's what the Rejected Ideas section is supposed to capture.
When I read the description of Rejected Ideas in PEP 1, it seems like it's more for ideas that have been rejected that are still in line with the overall PEP / motivation.
We can change PEP 1 if necessary to make people feel more comfortable in using the Rejected Ideas section to record objections.
The most effective cases where I've seen this done have involved putting an explicit "Do nothing" or "Preserve the status quo" heading under "Rejected Ideas".
Another related element is to list folks that contribute significantly to that aspect of the PEP in an Acknowledgements section - adding them as co-authors doesn't make sense (as being listed as a co-author typically implies endorsement), but having specific names listed helps people to feel heard as long as they saw at least one of the listed names stating their own objections during the discussion.
Cheers,
Nick.