One difference between this and the Red v Blue is that in the latter, both camps held reasonable claims to the heritage. Both were capable of running on suitably equipped classic Amigas and whilst OS4 became the "official" successor to 3.x in the end, MorphOS could easily have have been the one to do so.
On the other hand, the CUSA stuff is a total disconnect. Other than branding, there's absolutely nothing (at least nothing that has been publicly shown) to connect it to the Amiga or earlier Commodore machines.