Magnus's Alt ? Do you mean Magnus's 2nd or alternate account ? From what I know, if this 2nd, alternate account is banned/close, then the 1st, main account will be banned too. It's what I read from : https://support.chess.com/article/596-can-i-have-multiple-accounts
2 months ago, @SinisterMagnus hit the #2 on the leaderboard, just behind Magnus Carlsen. There have been speculations of it being Magnus' alt. @GothamChess covered a video.
“Hopefully it is not a cheater" - GothamChess
That week, the owner has closed his account and stated " Closed: Inactive"
Last week though, I noticed the account as reopened.
Today, the account has been closed for fair play.
Wow.
🚫 Closed: Fair Play
This account has been closed for violating our Fair Play Policy.
These rules help keep chess fair for everyone.