There's no way to know what kind of nen abilities Chrollo has up his sleeve. Meruem is incredibly powerful but that doesn't mean some chump character with a very specific ability can't technically defeat him. Like the "red robe" that can shrink stuff and trap it, the one Chrollo stole, technically speaking if you got the king with that it would be end game no matter how strong he is.
So again, there's no point on bashing opinions when it comes to characters which we know so little off. Of course taking the king down could've been done incredibly easier if Netero wasn't so set on proving himself and giving one good last fight before dying. Like a bunch of really good plans could've been created around Meleoron, he could've gathered so much intel it's ridiculous. Imagine grabbing the king with with some whatever ability when he's playing fucking Gungi?
Legit, to be fair they were running out of time so getting enough intel to be able to know Meruem was playing Gungi and at which time he was might have been difficult but a Meleoron+Knov combo could've certainly trapped Meruem in Knov's room dimension and let him starve to death or whatever.
Personalitywise, he's pretty much the same as in that picture considering how sure he was that Gon would live.
His design was all over the place before the election arc though, Togashi usually takes a while before settling on a design but even taking aging into account he looks nothing like his earlier self.
he used to be clean cut but now he dresses like he doesn't even bathe regularly.
i think when he had gon he was optimistic about exploring other places but then reality hit him when he couldn't go to the dark continent.
get out of here Conor