After watching the encounter three times, my reasons for siding with Mailer and of distrusting McLuhan have become clearer. Firstly, unless McLuhan is a rambling old fool, he seems to be using a number of techniques of the rhetorical sleight of hand variety. His main weapon is to use words in a way as to render them virtually meaningless.
In one part, he makes a great play of the importance of the artist, and of the artist's role in culture, contrasted with that of the scientist, and we are presented with some kind of axiomatic dichotomy of categorisation - only for this to be completely undermined moments later, when he is asked which of these categories he falls into. Now suddenly, it is unimportant. In some ways he is a scientist, in others an artist. Therefore, these archetypes do not apply to himself, begging the question 'who do they apply to?'
In a similar vein, McLuhan states that it does not matter if we call something 'war' or we call it 'peace', to which Mailer retorts that it is of utmost importance, for if not, we deceive ourselves and, if we cannot agree objective definitions, we preclude the possibility of meaningful intercourse. How can we discuss war, if there is no agreed definition of what war is?
Perhaps I am reading too much artifice into McLuhan with this example, but early in the discussion, over the effects of information overload, he throws out the supposed opposite meanings of the word 'cool', which I take to be (1) lacking in warmth, (2) hip, worldly-wise. Later on, he uses the word 'cool' to describe his attitude towards questions of morality. Mailer is attacking him for the absence of any judgements of what is right and what is wrong. By McLuhan's logic, his own lack of moral judgement is 'cool' - but does he mean dispassionate, or hip? It is not clear. Furthermore, it is intentionally ambiguous, which comes to the main problem with McLuhan - his desire to substitute ambiguity for clarity, and to undermine rational discourse.
Mailer, on the other hand, is a man to whom moral judgement is of vital importance, indeed it is central to the artist's role in culture. The artist is not someone who merely looks for new patterns and categorisations, but one who takes a step further and decides if something is right or wrong.
I am much more familiar with the work of Mailer, and it would be foolish to judge McLuhan's oeuvre on this one encounter alone. His concept of information overload leading to categorisation is enlightening, but give me a man like Mailer every time. He may not always be right, he may be too fast sometimes and too slow others, but McLuhan's system tells the time like the proverbial broken clock, and as such serves no useful purpose to man, no matter how well-crafted the dial.