Restricting the command that way is useful, but perhaps more restrictive than necessary; and probably hard to remember to update. rsync also comes with `rrsync` which allows you to restrict to read-only, write-only, no deletions, stay in a certain directory, etc, without needing to grab the exact list of flags rsync uses under the hood, nor require you to remember to update authorized_keys when you change one tiny flag on the sending size.
[1] https://download.samba.org/pub/rsync/rrsync.1