My question is, where are the MPQs?
Gone. Deleted. No longer useful. Not needed.
Warcraft III has moved to using CASC like most Blizzard games. If Vexorian left the source code for his optimizer it would be trivial to fix...
If one wants to use Vexorian's Optimizer one needs to download an old install of Warcraft III, e.g. from a disc. That said the tool is very bug prone as many of the JASS optimizations will break modern maps due to incorrect assumptions.
I know they changed the file system to CASC but I can't locate even the CASC files... lol.
The CASC local storage is located at
Warcraft III\Data. The data sub folder contains the archive storage and the
config sub folder describes various entry points such as the identity of the TVFS files which make up the file system.
I suggest forgetting about Vexorian's Optimizer. Instead use a tool like
W3x2Lni and publish the "slk" form of the map. W3x2Lna needs updated data to support 1.31 which includes extracting the required data files as well as changing the settings file to use the extracted data files. This should give you pretty decent "protection".
If you just want quick and dirty "protection" then use MPQEdit to delete some editor only files such as the (listfile) and GUI trigger data file.
It is your responsibility to make sure sufficient editable backups of your map exist. These should also be handed to trusted individuals in case something were to happen to you that would prevent you from performing critical fixes to the map in the future.