He appears to be talking about "a full re-wire" of the wiring, but withput replacement of the CU. As I've said, probably not all that sensible - certainly not common - but, there again, what he has subsequently written suggests that he probably would not need "a full re-wire" (of any scope) in order to make the installation safe.If you are doing "a full rewire", then the board will be replaced.
Kind Regards, John