We've been given 3 possibilities, you're giving 1 possibility; you're wrong in this case.
We have been given two possibilities of 'nen staying behind', and this has been referred to in the manga by the phrase 'nenstayingbeihnd' and 'nengettingstronger'.
Those two things have been used equivalently.
That is what i am saying from the beginning on.
They are used for the thing phinks describes.
Which is a CASTED NEN ABILITY which STAYS BEHIND and MAY GET STRONGER.
Emphasis on the CASTED. So i have proven you that this has been referred to as 'nen getting stronger'. Which is what machi thought.
Which is nothing about hisoka getting stronger.
So we have seen that the spiders know about nen getting stronger after death, which refers to a casted nen ability.
And we then saw machi thinking 'nen getting stronger' when she noticed nen flaring up in hisoka's body.
Which shows us that she thinks a casted ability of hisoka has stayed behind and got stronger.
That has nothing to do with her thinking that hisoka as a nen user got stronger.
She has to think hisoka is dead for the nen ability to get stronger.
And Hisoka WAS DEAD at that point, because that was shortly before his ressurection.
So exactly what is said happened: Machi thought nen stayed behind and got stronger (which it did), and THEN hisoka ressurected himself with that nen which got stronger, which refers to the bungee gum in his body and on his fingertips.
After that, Hisoka is back to normal and the treads vanish. Every nen he uses after that is absolutely normal, because it has nothing to do anymore with the nen that was left behind.
Well, you're wrong.
Nen getting stronger after Death was stated by Phinks to be possible, she clearly knows about this phenomenon, and we've seen the result of it. Hisoka doing things that he has never done until this Resurrection. There's correlation with every action and they complement each other with that premise in mind.
What you're doing is merely making excuses to state that Togashi didn't create a plot-hole when it is the reality.
Yes, Machi knew about nen getting stronger, but only in the sense of a casted ability.
It has nothing to do with what you think it does.
And it is completely illogical to think that.
Machi cannot gauge hisoka's strength because he was dead at that point.
She also could not see any new nen ability.
How would she even know hisoka got stronger?
It makes absolutely no sense that she could judge that. THAT would be a plothole.
You're simply playing a game of semantics.
When Morel asked Gon to show off his aura during the ant arc, he was more or less asking him to show off his strength.
Nen belongs to the user, so it is their power.
If their Nen is stronger, then so are they.
Gon trained his Nen to be stronger, so he is stronger.
You're simply beating around the bush.
I am not playing semantics, i am looking at the facts in the manga.
The nencapacity someone can show has nothing to do with nen staying behind.
Nen staying behind is something like a curse, and even very weak nen can get strong after a useer died, for example if he held a grudge.
You have it the false way round.
Gon did not train his nen so he got stronger, gon got stronger, and so did his nen.
He trained his body to be able to keep up nen output steadier and stronger and thus had more nencapacity at his disposal, and he also trained to be more accurate with his usage of nen.
It is his body that got better at nenoutput and nenusage.
In the case of nenstaying behind however, the body is dead. The nenability alone gets stronger.
To think that hisoka got stronger after that would mean that you think something in his body changed just because the bungee grum treads arround his fingertips got stronger after his death.
But that makes no sense. The only reason hisoka is alive is because he used nengettingstronger to CPR him.
The nen he uses now did not stay behind. It comes out of the same body he had before. No more training, no stronger nen nodes, no more refined abilites.