it should be noted that there is no rootcopy cheatcode. it's automatically picked up if there's files in the rootcopy folder (structured in a proper fakeroot to do anything meaningful)
norootcopy is just another part of the suite of "alway fresh" cheatcodes that only has an effect if there's files in the rootcopy folder, otherwise it does nothing (in essense: no files in rootcopy = norootcopy)
and for completeness: rootcopy=/path/to/rootcopy is only to define a non standard location for it.
probly not this one exactly.
if testers boot their ISOs with it, they should be very careful about what they put in rootcopy ... preferably nothing (that goes for whatever filesystem you use)
there is a sure way to find out: try it backup the original and if there's a problem, it's easy enough to swap back..