I’d imagine its beyond an opinion; they made a claim these cards were printed in 1996 and they weren’t. It’s one thing to hide behind an opinion on something subjective like condition. However, dating an item isn’t a subjective opinion. CGC made a definitive claim, “these were printed in 1996” when objectively they were not.
I don’t know what the exact angle would be, perhaps gross negligence? How did a lopunny collector provide a better answer by looking at scans on his computer than an entire authentication company, with every authentication tool at their disposal, who had years to figure this out. It’s so comically incompetent.