How come the CSPPC emulation in WinUAE is so incomplete it won't run MorphOS 1.4.5 but does manage to run OS4?

Are they writing an OS4 emulation platform or an accurate as possible Amiga+Expansion Hardware emulator?

I always thought is was the latter but now i i'm not so sure. If they were aiming for accurate Phase 5 hardware emulation then it should be able to run MOS1.4.