You are correct on the UPS SKU's (they always needed to be edit BOM'd). However, the "mandatory" SKU's within the PDU section as part of the ATO editor are new.
The problem with this is when dealing with all of the associated services, containment, etc. It's just MUCH simpler to drop a PX40 in the row, edit the PDU and then edit BOM the UPS out.
This worked previously, as I had a design expire that needed updates and I was forced to go the RPP route, where I had previously approved an edited PX40 PDU.