I think what he means is they'll expect the 2D frame trap after 2C, and use some method to avoid it entirely. Instant blocking 2C isn't hard, so they could jump, many characters can reversal, guard point, or even jab out.
5D, on the other hand, has a hitbox and properties that prevent many of these options. It'll still lose to reversals, but it's second hit may help in preventing guard points, and it's air unblockable first hit will catch jumpers and moves that hop over low hitboxes (Noel's 2D comes to mind).
That kind of variety is what he's talking about, I'd expect.