I think he was trying to make the point that the word "power", when used about programming languages, is either:
1) Well-defined in terms of computability, but then rather uninteresting, since all programming languages are Turing-complete.
or:
2) So ridiculously ill-defined as to be meaningless.
Instead of arguing about which language is the more "powerful", one should be arguing in terms of which sets of problems have efficient (in terms of programmer time and maybe learning curves) solutions.
