When a member's account is disabled, all of their notes will still be accessible in Fellow. Other members who were a part of the meeting will still be able to view and edit the notes fine. You will also be able to search for the meeting notes using the search function in Fellow as well if you're trying to locate them.
The member whose account has been disabled will not be able to access the notes anymore, however, since they are not able to access their whole account unless their account is re-enabled.