The Measure, and the Measurer, of All Things

Since Nietzsche seems to nowhere engage his famous anti-Platonist predecessor, Protagoras, it can only be speculated that his doctrine includes the grounds for three disagreements with the formulation 'Man is the measure of all things'.  First, it follows from the doctrine that an Overman can also be such a measure.  Second, it qualifies 'man' as 'some men', i. e. distinguishes those strong enough to be a source of Evaluation, from those who are not.  Finally, it suggests that a man might be the 'measurer', but not the 'measure', i. e. someone who creates a normative ideal, but who himself is not that ideal.  Arguably, Nietzsche classifies the following as notably exemplifying that Measurer-Measure relation: Moses-Decalogue, Plato-Form of the Good, and Kant-Law of Reason.  None of the three disagreements is easily reducible to Protagoras' formulation.