It's ten lines of code that provide their own implementation, meaning you can adjust the behavior in any way you want and that it works anywhere Emacs is supported, even MS-DOS.
A lot of similar use cases are already fulfilled by the built-in functions sort-fields, sort-columns and friends.
Of course you can also enter your external sort command by selecting the text and pressing C-u M-|. Emacs knows how to use external processes. It's very flexible.