That part is right, if not for him, at least for their followers. They couldn't handle H.U. v. Balthasar and or imagine that a minority of Catholic thinkers was doing the very job that Schaeffer hoped for (in the 50s).
The evangelical disaster was just that, a disaster. In truth, their diagnosis is no longer knowledgable enough to mention Plato or Aristotle. In the end, they could still tell the fish was sick (they followed S. this far) but their prescriptions today come in the same bottle from the best psychologists.
The distinction between Plato and Aristotle cannot describe Schaeffer's critique on modernism. Modernism--not Platonism--was the name of the pig that Schaeffer chased.
Of course many modernist like to claim Aristotle as a rationalist. But to say the Aristotelian view of reality is to be identified with rationalism is merely a rhetorical claim which the author picks up unwittingly. exmarine recognizes this problem.
If Platonism got bad rap from Sch. & Co. , it was second hand knowledge that caused it. It was the old despisement of the material world, so familiar to anyone who hasn't read a stitch of Plato or Aristotle, which they thought wrong. It happens that Aristotle thought it wrong too--and even Plato. Going against the "platonists," Aristotle claimed to search for the human good and not something out of human reach. And yet what does he suggest is the best life in book 10 of his Nicomachean Ethics? The highest good is to live most like the divine. In this sense and this sense alone can he be a rationalist: reason was the most divine part in us.
Aristotle dismissed "man is the measure" thingy although some think his practical reason is just that. It isn't. He thinks it is ludicrous to think the human person is the supreme being in the universe and explicitly says so.
As for Plato, few remember what he wrote in the Timaeus. Or the Symposium. Both books wrestle against the despisement of the body that Socrates gives in the earlier Phaedo.
It was an ascetic strain in evangelicalism that S. struggled against (the source of that strain would first lead to the 19th century, not 4th c. BC.) And so what Catholics already had, they admired the Renaissance, they wanted the faithful to relish the body like Rembrandt, they wanted the somnabulant and undisturbed suburbs not only to grow geraniums and light candles for christian Fahrvegnügen, but also to listen to Beethoven and go to the museums. Even more than that, they wanted their own to recognize the "existential methodology" that had permeated their thinking--unawares. It comes in like London fog, he said.
If there was mysticism in that fog, it was in the form that separated hope and optimism from reason. This too was a problem for their own. And so the pig got a real name: Barth. Of course the Catholics hosted their parasites as well: Kantians.
Your post is quite interesting. I would not agree with your assessment of Aristotle however. Since Aristotle was a pagan, he could not hold to true philosophy - that must be revealed from heaven. If Aristotle truly believed in a Supreme being, he had no idea who that being was. As Schaeffer pointed, out the Greek gods were small gods with limited powers.