Comment by CGamesPlay

Please correct me if I'm am wrong, but POSIX doesn't define a non-interactive or interactive shell, it only defines a login shell. You can't "set your non-interactive shell", only "set your login shell". OpenSSH could easily have decided to "join all arguments with spaces and pass them to sh -c", which would also have been a bad decision for the reasons listed in this article, but instead chose the even more esoteric choice of using the login shell, even when running non-interactive commands.