This tutorial not really overriding the plugin, instead it create copy of a plugin with rename in to project directory and run it as a project plugin, allowing you to modify plugin code without modifying one in engine source code. This method is only OK if you plan if modifcation are only for specific project (you free to modify engine source code for game project), but you can not redistribute it alone (aside of secured GitHub engine source code fork), so it not suitable for unreal marketplace.
Plugin it self needs a overriding function like that, if it does not i can not be overrided.