Contour in the context in which -=A=- used it is interchangeable with the word conform; go back and look. While I do not pretend to speak for him (or agree with what he said), I highly doubt he intended to use the "acceptable idiomatic expression," which, to be very precise, would be "cater to your every whim." That phrase is nothing like what he said; catering implies servicing, while conforming (and certainly contouring) implies yielding. I doubt he meant he wouldn't be of service; what sense would that make? I believe he intended to say exactly what he did say, by which he clearly meant he would not yield to others' points of view.
I strongly disagree that "altering an idiom generally reduces the effect of an argument, rather than enhances it." Who says? Quite to the contrary, the use of cliché idioms reduces the effect, or strength, of any argument. Any single argument is more forceful when it does not rely on such pap.
And for the record, I pursue this only because I felt the word contour was being maligned, not -=A=-. The English language is a very subtle thing, capable of limitless variety; I'm quite in love with it, and I felt it was being unjustly restrained. This interest is quite separate from the content of who said what.