With the new approach, you should first uninstall grub-btrfs and install it from sources (as mentioned in the blog post). The additional line in /etc/fstab is no longer required. There’s a new service (no more grub-btrfs.path) and a small change to the configuration of the new service.
If the current setup works for you, then I wouldn’t change it. However, if the AUR package of grub-btrfs is updated, you will have to perform the new steps