I don't remember CGC saying that pressing was not resto, it just could not be detected, so it wasn't noted on the purple label. Asking other companies to disclose if a book being submitted was pressed? Those companies have no responsability to do so. But if CGC (or a CGC-owned entity) is providing that service & it is known, I would think it must be disclosed. If not on the purple label (highest level of disclosure), then at minimum in the graders notes (hidden from view, but available for a fee).
Would that put CGC at a possible disadvantage? Sure. The books they pressed would be disclosed as such, but if the book was pressed by Company X, it goes through undetected. It would give CGC a leg up in the integrity column, but there's not a whole lot of $ rolling in from being honest. I can't imagine that they would buy a service and then put books that went through it at a disadvantage within the hobby.
Looking for a silver lining, do you think that the census numbers will come back to reality? If books are given to Matt still in slabs, the old # could be removed (not sure if he currently submits labels with pressed books).