I think that is at best fragile as a general statement. I would argue that increases in local support are dependent on other factors besides heavy-handedness or harshness, and that these vary on a case by case basis. For a plethora of counter-examples see:

The history of the Jewish people, Native Americans during colonialism, the anabaptists or the calvinists in European history, the Muslim populations after the conquest of Granada.

I keep wondering what China is going to do when these efforts fail (genocide being the primary worry). Xi's dictatorship will only grow more powerful and oppressive in the next five or ten years, as is nearly universal with the history of dictatorships. I don't believe China will be able to strip away the religious beliefs & culture easily, nor near-term. The only way they can do it, is over a very long time frame, and by trying to forcibly prevent the next generations from becoming Muslims.

As news of what's going on there spreads globally, to the Middle East and other bordering Islamic regions, China may have to build considerable border fortifications to keep terrorists out (people seeking revenge, or just an excuse to wage jihad, and attempting to flow weapons in). China of course borders Pakistan, Kazakhstan, Afghanistan, Kyrgyzstan, Tajikistan - all Muslim majority nations.