Would the original authors of Unix agree with your opinions on how to define the term?
Does AT&T's c. 1980 port of Unix to run on top of IBM's TSS/370 mainframe operating system [0] count as a real Unix? It appears that Ritchie did think it was a Unix, he linked to the paper from his page on Unix portability [1].
So is your definition of "Unix" broad enough to include that system? If not, you are defining the term differently from how Ritchie defined it; in which case I think we should prefer Ritchie's definition to yours. (McIlroy's maxims are explicating the Unix philosophy, but I don't read him as saying that systems which historically count as Unix aren't really Unix if they fall short in following his maxims.)
> McIlroy's maxims are explicating the Unix philosophy
This is why I used the quote, not for this reason:
> but I don't read him as saying that systems which historically count as Unix aren't really Unix if they fall short in following his maxims.
I'd say yes, a port of v7 is fine, because it's not meaningfully more complex. It can still be comprehended by a single individual (unlike FreeBSD, Linux, everything currently called Certified Commercial UNIX trademark symbol, etcetera).
> I'd say yes, a port of v7 is fine, because it's not meaningfully more complex
I think AT&T's port of V7 (or something close to V7, I guess it was probably actually a variant of PWB) to run on top of TSS/370 really is meaningfully more complex because in order to understand it you also have to understand IBM TSS/370 and the interactions between TSS/370 and Unix.
Does AT&T's c. 1980 port of Unix to run on top of IBM's TSS/370 mainframe operating system [0] count as a real Unix? It appears that Ritchie did think it was a Unix, he linked to the paper from his page on Unix portability [1].
So is your definition of "Unix" broad enough to include that system? If not, you are defining the term differently from how Ritchie defined it; in which case I think we should prefer Ritchie's definition to yours. (McIlroy's maxims are explicating the Unix philosophy, but I don't read him as saying that systems which historically count as Unix aren't really Unix if they fall short in following his maxims.)
[0] https://www.bell-labs.com/usr/dmr/www/otherports/ibm.pdf
[1] https://www.bell-labs.com/usr/dmr/www/portpapers.html