Read the post you linked, read it again, follow each and every instruction, don't miss one, don't decide maybe it's not necessarily important to do a step.
What it does, essentially, is instead of booting your Wii U menu it boots the vc game you installed instead, because the vc game has been changed, via haxchi, it boots either, a custom firmware (cfw(custom menu)) which is exactly like your original menu but with some hacks (iosuhax, sig patches, etc), or a rednand ( a clone of your original system menu on sd card), or a fw.img err...something else.
Deleting the vc game redirects to nothing, Brick. Removing haxchi redirects to just that one game only, Enjoy. Updating your Wii U could break haxchi on the game, Brick.
It is the easiest way to brick, if you don't follow the instructions, as it requires no knowledge and a simple install of cbhc off hbl. And requires you to not update (just incase).
As long as you follow instructions and block update's it's safe.