There's a reason guides like this are a dime a dozen - there is no way to generalize server configuration this broadly.
But as long as we're doing it anyway - the only thing that locking the root account gets you is assurance that if you ever bork the user you created in this guide (or sudo functionality as a whole) you'll have no way to recover without booting into another environment.
Perhaps one ought not take sysadmin advice from a blog post with a first sentence that reads "I’m not a sysadmin, and I don’t want to be".
But as long as we're doing it anyway - the only thing that locking the root account gets you is assurance that if you ever bork the user you created in this guide (or sudo functionality as a whole) you'll have no way to recover without booting into another environment.
Perhaps one ought not take sysadmin advice from a blog post with a first sentence that reads "I’m not a sysadmin, and I don’t want to be".