What does a la carte mean as an adjective or figuratively?

Dictionary definitions of à la carte tend to focus on the approach that many restaurants adopt toward their offerings, in which they price menu items separately and let customers select from among multiple options for different courses (for example, appetizers, soup/salad, main course, and dessert, as well as beverage pairings) of the meal. For example, The American Heritage Dictionary of the English Language, fifth edition (2010) has this entry for the term:

à la carte adv. & adj. With a separate price for each item on the menu. {French, à la carte, by the menu}

And Merriam-Webster's Eleventh Collegiate Dictionary (2003) has this:

à la carte adv or adj {F[rench], by the bill of fare} (1816) : according to a menu or list that prices each item separately

The implicit distinction here is between à la carte, on the one hand, and prix fixe ("fixed price") on the other. The Eleventh Collegiate defines prix fixe as "a complete meal offered at a fixed price; also : the price charged." The key feature of prix fixe is that it is a take-it-or-leave-it proposition: customers buy the meal that the restaurant offers that day or they do not; the customers has no options at a more granular level.

Used figuratively, à la carte means something like "skipping around through a series of options and choosing the ones you like." So the author quoted in the posted quotation is saying that the Republican Party in the U.S. is being urged (by "reform-minded Republicans," the article says) to select its positions on sociopolitical issues one by one, on the basis of their cultural popularity or other criteria, rather than adhering to a fixed and (supposedly) consistent program of policies based on a clear worldview.

I read the author's "à la carte" language as being hostile to an à la carte approach and as endorsing, sub silencio, a prix fixe alternative. But in doing this, the author fails to address the fact that someone—or some group of people—must do the selecting of the items that appear in a prix fixe meal, as surely as individual customers choose the elements of the meal that appears on their plates when consulting an à la carte menu. The essential difference is that the restaurant decides in the prix fixe case, while the consumer does so in the à la carte case.

What makes this particular quotation rather odd, when you think about it, is that the Republican Party is somehow both the restaurant owner and the restaurant customer, figuratively speaking. The author implies that the GOP should resist adopting an à la carte approach to the platform that it runs on—as if the party hadn't already worked through various political options à la carte in arriving at the prix fixe menu that it currently offers voters. The only way to avoid running onto the shoals of à la carteism at some point in the process, it seems to me, is by viewing the political prix fixe menu as being the product not of multiple discrete choices, but of some absolute, unconditional, uncompromising force—as being, perhaps, the result of a series of logically necessary conclusions dictated by a consistent moral compass that transcends political considerations.

The author's underlying argument seems to be that, in endorsing appropriate life templates, the GOP should refuse to consider an option's sociopolitical popularity—and its potential bearing on Republican candidates' electability—and instead be guided by a higher authority. Whether the author actually believes this argument is a matter for conjecture. I suspect that it's considerably easier to criticize the expedience of à la carte political relativism than to explicitly defend the actual mechanics behind prix fixe political absolutism.