From the protected question FAQ:
Users with the Protect Questions privilege (15k reputation on graduated sites, 3.5k on beta sites)
- can protect a question which is at least a day old, and has at least one answer by a new user (i.e. a user with <10 rep on the site, or <110 rep if they have the association bonus
Suspended users have 1 reputation. For example, one of our old members Athari (https://ru.meta.stackoverflow.com/users/176051/athari) has been suspended, and I can now protect any question that they have answered, and that have no other answers from new users (e.g. Кому надо это [node]?).
But they're not a new user. Is this intentional, or is this a bug?