Rational Choice Theory is the claim that the economic behaviour of groups can be best modelled by assuming each individual is operating in their own rational self-interest. It is where game theory originates, and is more or less adept at explaining the fluctuations of markets.

Rational Choice Philosophy goes beyond this to offer a prescription for how one ought to live one's life. It emphasizes the moral supremacy of rational pursuit of individual goals. Beyond merely describing how groups behave, it argues that it is good that they act in the manner described. It holds that the best outcomes are those generated by each individual pursuing their goals rationally. It forms part of the moral foundation of libertarianism, and is the genesis of such notions as the supremacy of private charity over public services. From the RCP perspective, it is morally preferable for individuals to make a rational choice to donate their time or resources to further a desired goal, than for a government (or collective) to impose those choices upon all people.

As the author states, a rational extension of this moral imperative is that individuals should seek to maximize their own power, so as to be better able to achieve their goals. This is the moral backdrop that has framed the common narrative in America, certainly since the Reagan years if not earlier. While it may seem a natural thing to believe, it is only so because of its pervasiveness in the culture that shapes our moral judgements. By contrast, in China a person who advocated RCP would be considered greedy or selfish. There, community, family, and cohesion are more highly valued. This too is a product of their shared narrative.

The author's mention of quantum mechanics is sloppy. In the Great Free Will Debate, a Newtonian determinism had seemed to spell the end of free will. If our choices are the product of electrochemical processes in our brains, which are determined by our genetics and environment, which all essentially come down to atoms smashing into eachother, then everything that will ever happen was determined at the Big Bang and so free will is an illusion. It may be a convenient illusion that has been evolutionarily beneficial, but it's an illusion nonetheless. Then, quantum mechanics came along and poked holes in determinism. Some atomic processes may not be predetermined, and are instead functions of probability. This didn't save free will, as random chance is still beyond the control of the agent, but it did call determinism into question.

What I suspect the author is getting at is that he (implictly) argues that the ability to make a rational choice depends upon the ability to know the effects of a given cause, which may not be possible if quantum processes introduce randomness. There's a couple problems with this: 1) nobody has ever shown quantum effects at a macro scale (Herr Schrodinger's cat notwithstanding), and more importantly 2) the ability to make a rational decision does not depend upon a perfect model of cause and effect. Reason need not be deductive; it is enough to make an educated guess about the state of the world and the effects of one's actions effect upon it.

The author didn't prove his central thesis, that RCP has failed. That would entail a far deeper inspection of the philosophy than was done. He did, however, make some interesting observations about it, namely that our common belief that it is good for us to act according to our desires was deliberately fostered as a counterpoint to Marxism. That's not a condemnation of the philosophy itself, however.

As for Ayn Rand, the author may simply have been saying that her ideas gained far greater prominence after the deliberate campaign to foster a moral philosophy of rationally pursuing one's individual desires.