Because of prejump frames where you can't block and you're also not allowed to block for a little bit right after the jump comes out either, so if you try to jump to escape the throw but Potemkin does c.S instead, you're gonna get hit and explode
Also normally you have enough throw invuln frames after blockstun to jump out, but guard crush doesn't give you that throw invuln like normal blocking does
4:18 btw you can special cancel (and jump cancel) red assault so going into fafnir there is pretty good I would imagine. Sol in general takes advantage of red assault MASSIVELY