Here is a link to what A40 means:
https://www.porscheclubgb.com/PCGB/media/R31%20assets/Docs/Porsche_Approved_Oils-May-2012-A40.pdf?ext=.pdf
updated here, doc is garbled but the Posts cover the gist of it:
http://rennlist.com/forums/996-forum/923972-new-2015-list-of-porsche-approved-a40-oils-and-a-strange-change.html
The list does not include some oils that exceed the A40 spec for the M96 specifically.
The benchmark for comparison of M96 oil is JGDT40 according to the M96 experts.
Obviously the engine will not explode as soon as you fill it with something else but unless someone is both a tribologist and an M96 expert,how can they credibly contradict the experts and mislead(perhaps) other Forum members ?
I am neither a tribologist nor an M96 expert,I just pass on a digest of many prior discussions of this subject.