I’d be interested in the script, as I have quite a few WP sites whose owners are typically slack about updates, so I make myself an admin user and do them myself.
I agree that it doesn’t have to be part of Sympl, although I appreciate the security support for WP that is built into the standard Sympl apache2 config.
(edited to add: is the script basically the 3 lines quoted above? I don’t know anything about wp-cli)