There are two distinct questions that need to be treated separately:
What did Aquinas teach?
Is Aquinas’s teaching (regarding physics, metaphysics, whatever) defensible today, in light of modern knowledge?
The dispute between the one group of Thomists and the other group is first and foremost over what Aquinas taught, though the other question sometimes get tangled up in the debate, because the Thomists are usually just as interested in showing that Aquinas was right as in determining what he taught.
If we focus on the question of what Aquinas taught, forcing ourselves to refrain from judgment regarding its correctness, the question is whether Aquinas’s understanding of creation, nature, matter, form, etc. is compatible with:
(a) the specifically Darwinian understanding of evolution;
(b) any form of evolution.
Chaberek, against many current Thomist philosophers, argued that Aquinas’s understanding of creation and of nature is such that it is incompatible not only with the Darwinian understanding of evolution, but with any understanding of evolution in which purely natural causes bring about changes in the substantial nature of a being. In other words, for Chaberek, you can have Aquinas, or you can have evolution, but you can’t have both.
So the question become an exegetical one: who interprets Aquinas better, Chaberek and Torley, on one hand, or Feser, Beckwith, Austriaco, etc. on the other?
If one decides that Chaberek is correct, then one has to say either that evolution is a major error or that Aquinas’s understanding of creation, nature, form, etc. contains major errors. If one decides that Austriaco is correct, then one can have both evolution and Aquinas.
If your theological orientation is such that Aquinas doesn’t automatically have to be right about anything, then the debate will be of less importance to you. But it’s a bone of sharp contention among those for whom Aquinas is believed to be incapable of serious error. If evolution is really incompatible with the thought of Aquinas, then the Thomist must dump one or the other, and the price for either choice is higher than most Thomists today are willing to pay (either being laughed at by the world of secular science and scholarship for rejecting evolution, or being shunned by their Thomist colleagues for admitting that Aquinas was wrong on some very central matters regarding creation and nature). So it is not surprising that many Thomists bend over backwards to try to harmonize the very different world views of Darwin and Aquinas. But Chaberek doesn’t care much about what the world of secular scholarship thinks of him, or what the majority of Thomist scholars thinks of him. He believes that the teaching of Aquinas logically excludes evolution, and he says so without mincing words.
Whether the fact that Chaberek is from Poland, and most of the vigorous defenders of a Thomistic evolutionism work in the Anglo-American orbit, has anything to do with his willingness to defy scholarly opinion, is perhaps impossible to determine.