Well, there's a watertight argument.
If you can't win with the facts, slander your opponent when baseless and unprovable accusations.
What a way to warm the hearts of non-Catholics to join the RCC.......
None of this is unprovable. The phenomenon of cafeteria Catholics is well known and much of this has been written about them. And of course Gays and Lesbians and the Feminists find the Catholic Church as the last bulwark against their perversity. Schools, colleges, the professions and media were all successfully brought into the Sodom and Gomorrah orbit where their lifestyle and liberalism was now orthodoxy.
Finally, the Anglican and Protestant Churches began to genuflect at their demands as well to say nothing of the Black Churches and their pastors. The Catholic Church like the Rock of Gibraltar has a Catechism that instructs homosexual conduct to be an intrinsically disordered evil. These then are mostly your ex-Catholics.