Honestly this is ridiculous people managed to convince themself that someone who was leader of the most dangerous prison in the world where there are shishibukai, revo,pirates wasnt a top tier even though its literally the level needed minimum to rule such a prison. Now tha oda remain loyal to that portrayal and put him against garp they are downplaying shiryu even though they know well that this wont end well for garp and shiryu will stop him somehow. According to them its fine for kuzan to fight garp ( even if he got help they will headcannon it into he did it alone) but shiryu the actual second strongest vs garp is untinkable for them Lol.