Deleting Backups from Additional Destinations?

This morning, cPanel Backup backed up about half the accounts on my server and then ran out of disk space. During this process, cPanel Backup did as instructed and uploaded those backups to an Additional Destination (an FTP site at my home). Here's my problem.... cPanel Backup then logged into my home FTP site and DELETED last week's backups.

I've read this documentation a dozen times and I see nothing to indicate that this is the expected behavior:

Further, I have found no checkbox that lets me tell cPanel to DELETE local backups but PRESERVE remote backups. Is the only option to REVOKE deletion privileges from the FTP account my cPanel server uses to upload files?

Finally, here's the e-mailed report I got from cpbackup:

 

Honestly I was expecting the "Retain backups in the default backup directory" setting to only affect LOCAL backups since space is often at a premium. I was not expecting it to do anything to REMOTE backups, since I could write a cron job on that server to prune old backups.

But even if you believe that "Retain backups in the default backup directory" should apply to both local and remote servers, the script should absolutely not prune remote backups until the new backup has been successful!

The backup script failed about 1/3 of the way through the new backups. Then it completely deleted the folder of last week's backups on the remote server. Rule #1 of backups -- don't delete the old backups until you confirm you have new backups.