Good question, you're allowed a second account, but only if you get it approved by chess.com first. This is my second account, but I never had my first one USCF registered so not sure how that works
New accounts

Although I don't know if there is a specific rule about this, I can't imagine there is any reason why your friend shouldn't be allowed to do this. They'll likely just remove the old account under their name and replace it with the new one.
This isn't even really a "2nd account" if the 1st one is closed and replaced by another. It's not like you're asking if you can have 2 accounts simultaneously connected to a uscf profile.
Asking for a friend, if a member closes a Chess.com account and opens up a new one, can they be re-admitted to this group on their new account? I am not certain of this rule because of the admission process, so some clarification would be great. Thanks!