Yeah, that scenario and lifetime Platinums/Golds who haven’t flown paid tickets in the last year would also have zero EQDs. I’d think zero is the most likely tie value in the EQD category. And since even Golds do sometimes get upgraded, the fare class category probably does occasionally come into play when getting to the bottom of the Platinum part of the upgrade list.

Certainly seems plausible enough that it makes sense for AA to list a tiebreaker after EQDs. But not probable enough at all to justify a statement that premium economy trumps economy in the SWU upgrade order, especially for a customer who has non-zero last-12 months EQDs, the motivation for this digression.