Jia Shidao was extremely confident in the white-knuckle power his fists could deliver, so he didn't summon a geno core. The Iron-Fist Martial Hall was made famous by his Iron-Fist Slash, a brutal move when coupled with his fitness level.
He had even managed to max out his ordinary, primitive, and mutant geno points, placing his fitness level at over fifteen thousand. Eight thousand of those levels were from mutant geno points alone.
He believed his Iron-Fist could beat and destroy anything, even silver geno cores. He was impressed that Han Sen could create a bronze geno core, but he did not think he had any that were greater than that.
So, Jia Shidao was comfortable in the prospect of using only his fists. He did not think he needed to summon his own geno core. But he thought something was amiss the moment Han Sen lashed a whip-like item towards him. The item was frighteningly quick.