I can see the logic in that but the message doesn't help as it highlights options that are not available to teachers by default any more:
"Notice: You have selected to backup no users ("none"), so all the modules backup have been switched to "without user data" mode. Please note that the "exercise" and "workshop" modules aren't compatible with this type of backup, so they have been deactivated completely."
I suggest it's revised to meet your objective and to make it more appropriate to the new status of backups:
"This backup does not contain information from user profiles or user data from activities e.g. quiz attempts, forum posts, wiki pages, glossary entries, chat sessions etc. Please note that the "Exercise" and "Workshop" modules aren't compatible with this type of backup and are not included."
Please check the statement about exercise and workshop are correct.
Added Helen as watcher.