Oh, I'm so glad I've found this
I've always considered Hisoka to be Gon's most important mentor (I think the most important ones for Killua are Illumi and Bisky for different reasons but that's a discussion for another time)
He was the first truly strong opponent Gon ever saw. He was like a demon in the Hunter Exam Arc. And he stayed as a reference point, to this day Hisoka is just as mysterious and powerful, even more so now that he died
Before Wing, before Bisky, before Morel or Knuckle, there was Hisoka pushing Gon to become more powerful. He was the one that gave Gon a reason to become stronger, he was the one that protected Gon and Killua by forcing them to learn Nen at Heavens Arena because he knew they had no one to guide them and getting crushed so early would ruin his harvest. He might not be a protective mentor, a parental one, he is selfish and evil, but he was Gon's mentor, and he wouldn't have gotten so far without Hisoka standing as a example of what being strong truly means
So I think it makes sense why in this moment, close to his lowest ever, when he is projecting all his malicious intent, all his aggression, fury and sorrow, when he is trying to intimidate Pitou, Gon would default to emulating Hisoka, after all, he was the first person that ever struck true fear inside him. Kite taught him how to be free and be his own person, Wing taught him Nen and Bisky helped him perfect it, Knuckle taught him how to think during a fight and how to lose, but Hisoka taught him how strength feels
