For entirely critical systems, I by now rather generate a reviewable script and run that. Something along the lines of:

    find /backups/ -mtime '-30' -printf 'rm -f %p\n' > very_scary_deletes.sh

This gives you a static script with a bunch of rm's. You can read that, check it, give it to people to validate and when you eventually run it, it deletes exactly those files.