As an organizer, you can restrict the attendee's entry for a particular session by using the "Control who can join" session.
Kindly refer to the help article - Control who can access your event session (restrict session-based entry)
Restrict other attendees from the session. Only a host and co-host have these rights.
If they find someone spamming/abusing, they can report the person, and then the host can block them.