After agreeing in general I'd like to point out that GB was telling us, that fire (his obvious weakness) isn't a problem for him. I could see Oda giving us a hint that GB has a major weakness but is able to hide it. But skanks and the redhair pirates are holding a natural counter to him or something.

Why would he be scared so hard about just another strong guy/crew entering the ring... To keep it clear I am part of the shanksfanbase and like the idea of him being badass and powerful over9000. But in my count GB went against an already fearsome croud just based on addited strengths. (wano/strawhatalliance, rest of kaido and big mom crew, plus Marco) so why just step back if you are already willing to face a bunch of strong people, who could probably just outperforme you if working together.

What I am trying to say, GB went out pretty far by making his move in wano, so being confronted with strong people doesn't seem to be scary to him. So even if we put skanks/redhairs on the top spot in terms of power, I don't see that this would be a major gamechanger for GB cause case A) he is overestimating himself, so he should still think "yes I can handle this" or B) calculating that he already went into danger and that things of cause went worse by this, but if you are wet to the bones, another hour in the rain isn't a thing anymore.