It is very significant that MacAndrew admits, both explicitly and implicitly, that the ‘normally accepted’ mutation rate is calibrated by evolutionary assumptions.
This is especially apparent by his misleading claim about ‘counting mutations’. They are counting no such thing, since they haven’t, in this case, seen DNA mutate (change). Rather, the differences are merely assumed to be mutations, on the basis of their belief that humans and apes have in fact descended from a common ancestor