I think SCO (SCOC not SCOX) ported so much of their own and MS stuff from Xenix 2.3.2 to 2.3.4 over to SCO UNIX SysV 3.2v2.0 to keep MS Word working I can well imagine (and I think I recall) that MS got royalty kick for every SysV Release 3.2 x86 install.
Where are my rose tinted glasses...
I'm also skeptical of the comment at the end about MS getting paid for all x86 Unixes, I'm sure that was true for anything labelled "Xenix" probably not true for 286 and later SysV ports which were done outside of MS