I'm not sure yet but anyway...
Let's not go off topic.
Let's stick with the possible alts of Arcas. Aka nutildah, GP, CH and that other guy who is maybe from Indonesia.

Now have you examined thoroughly nutildah? And CH ? Maybe they are working together as a team?
Those two are always chatting away together or maybe to themselves.

I'm just saying don't exclude any possibility.
Are you Arcas? Seek only the truth however painful.

Don't get fixated on your first suspicion.

You see that outburst from the new nutildah account owner?
That's a sign you're on track.

Cross reference his account sale with his password changes.
Tell.me what you find.
Then cross reference those with CH and GP

When considering who is an alt or possible alt of another member then consider all available data.

Listing accounts for sale is a big red warning.
Follow the link above.
Nutidah = Arcas.
That is a far higher probability that it being CH as you speculated above.
But I wouldn't rule CH out.