First, thanks for that detailed explanation about that 64-bit context menu option. It's good to finally understand now.
I'm using a Surface Book, so I'm definitely using DOpus x64.
Initially, I thought your Notepad test was a bit weird because what I thought you meant would happen would be that when "File > Open" is selected, because it is notepad.exe running as "explorer.exe," that the context menus would appear somewhere in the dialog window. That test as we know now could not be done so my silly understanding is irrelevant now.
However, after reading your post above about the menus still showing up in the normal notepad.exe, that's when I realized I definitely misunderstood something! So, I ran Notepad, did "File > Open", and--hello! --right-clicked on a file in the dialog window and the McAfee context menus do appear.