If you set the root shell as you outlined, you cannot log in or
su - to root. You an, however, still use
sudo or even
su (without the minus).
Disabling root login is generally a good security measure. You should, however, make sure that you can access the machine in some other way in case of a system failure. When the system behaves strangely, root login might still work when normal accounts don't (that is, for example, why on most Unix systems the root home directory is not in the normal user home directory, but on the system drive).
You can probably still boot into single-user mode, but I am not 100% sure on this with current MacOS versions, you should check. If this is still possible even with a no-login shell, this is your way out of trouble and you can safely disable root login.
If not, it becomes a question of which death you want to die. Decide for yourself what is more likely - someone abusing your root account or your system malfunctioning to the point where you would need that root account.