The author (@Deuce) of the script in question would be the best one to clarify that comment, but from my perspective: classic_shell.js was written as an exercise it determining what it would take to write a command shell in JS that mimicked the default shell, at that moment in time, without changing anything in SBBS itself to address any deficiencies or extra difficulties one might encounter while doing so. A lot has changed in Synchronet since the time when it was written.
That script was written as a direct port of default.src (the Baja Default Shell) as an exercise in discovering what parts of the default shell were not available in JS... it was basically copied from default.src then rewritten line-by-line. In the corresponding position in default.src, you'll find this comment:
################################################################################ This shell is an imitation of the Version 1c command set/structure ## ## It also serves as an example of a complex command shell using the Baja ## command shell language ## ################################################################################