Thanks for the quick reply, but with respect, your reply makes no sense, although it sounds very impressive, lol.
As I said in my original post, the plugins load fine (without first manually setting the CPU flag as you explained) if I double click on the Maya app icon like most people would, they just fail to load and crash the program if I launch Maya 2018 from a mac terminal command line, or by double clicking on the "maya" executable hidden within the .app/bin folder.
There is a bug in your code, it is not a MacOS hardware or software problem, because your software works fine if I start Maya on my "old" setups like most people would, but, as I also said in my first post, the reason why I prefer to start Maya on my Macs with the terminal is that it allows me to change the QT skin on the Maya interface to a "traditional" light style, rather than the light text on black that is currently in vogue for many.
(On windows it is possible set startup flags in an app alias, so that's how I do it there.)
Incidentally, other Adobe software, and Blender, gives me the option to set a "light" interface style, I would like it if the Substance family had that option also. I'm not a big fan of reading light text on a dark background, it makes my eyes tired.