It seems the point is that flock is documented to have behavior that varies between platforms. If flock is documented as always providing advisory locking, then I think that is a documentation bug (it reads to me that it certain may provide only advisory locking, but I didn't find a clear statement that manditory locking isn't the result on some platforms -- it quickly points to perlport, in fact).
So, if flock is documented to behave differently on different platforms, then writing code that depends on flock being advisory is not portable (which it obviously isn't, in practice).
It looks to me like you missed the point. And I don't see where any technical point was "just refuted" when it could have just been checked by Moron. But I certainly could be missing something.