I think Gon had already lost his nen after sacrificing all his nen talent to defeat neferpitou. What Gon had now was a nen from AI Alluka, a different level of espcialist nen transfered to gon to heal him. And a theory in mind is that AI Alluka could have transfered another AI entity to Gon making Gon another host of Ai aside from aluka...maybe this is how AI calamity entities from the dark continent propagate. It is in the manga fact that Ai's get a host to survive. Gon may now not be an enhancer anymore, but now a especialist with an abundant nen from Ai.

Zygg Zoldyk could have brought AI entity from the dark continent transferring it along down the zoldyk  bloodline until it reaches the 4th generation of zoldyks, to  aluka.