Is it less ridiculous if we take "right of center" to mean "conservative" (and "left of center" to mean "liberal")? Because that's what's actually being said; McCain wants to perpetuate the idea that the majority of America is conservative, while at the same time being inclusive of those who are currently shying away from the conservative label. The narrative being that, the Republicans, having been identified as far-right instead of the center-right they would like to be known as, have lost two consecutive elections because the Democrats fashioned themselves into the only party of the center. In order to come back, the Republicans must be seen as a more acceptable alternative to the center *AND* portray the Democrats as being far-left; they must do both, at the same time, or else it won't work. Hence, the term "right-of-center", associating the Republicans with the word "center", but when contrasting to the Democratic Administration, only using the word "left" and denying the positive association.

Frank Luntz has built an entire career out of this kind of almost-subliminal wordplay, and he's approximately the last live person who just about every Republican listens to.