MorphOS does not "need" the clock, but applications may do.
If the clock randomly changes, then for examples file caches (e.g. OWB font cache) may be recreated or server data (assuming you´re running a server) may get corrupted. Also your private data (e.g. images) won´t be properly sorted by date.
Adding SetClockNTP to user-startup is a very bad advise, as it will have no effect or delay boot time. Depending on your network even both may happen. Without an internet connection it may cause applications in user-startup never get launched.
A better(proper solution is to save the folloing lines into a file named "network-startup" into the sys:s drawer.
;--- execute MOSSYS:s/network-startup
run DETACH MOSSYS:c/SetClockNTP ;---
This ensures the clock is set each time the system boots and you won´t have any trouble at all. All applications will use the right date time as long as the system is connected to the internet while booting. There is also no delay/wait while booting.
If you want to launch other applications, which need internet connection, just add them at the end of that file.
I think that you don't understand my question, if MorphOS doesn't need the clock or date/time I don't change the battery of my Mac, this is the problem that I don't want open the Mac but if there isn't possibility, well I'll open the Apple. Much apple but bad batteries.
This question is because the clock of my MacG4 PPC when I star MorphOS appear the date of 1994 and now I update manually to the current date but if MorphOS doesn't need the date update I don't want open the Mac because it is new I bought two months ago but new the sealed without opened for a machine with 10 years, and also I know how open the Mac and the time for it.