The Chazon Ish says that bezman hazeh we do not talk harshly to sinners, and certainly do not use any violence, but we try to be mekarev with Ahava. This is not a story, he wrote it himself in his sefer on Chulin.
Second, Remember that the Chazon Ish passed away over 50 years ago. Pants may not have been the norm for women back then, as they are now for many. Back then, people may have been shocked that such a thing existed. Now, most people probably have never known a time when women didn’t wear them.
Third, quoting a difficult gemara, and then insulting those who say they dont understand it or can’t believe it is completely wrong and underhanded. As others pointed out, even the gemara was not complimenting the father who did that. But even if he was, there is a Chazal that says kshem shemitzva lomar davar hansihma, kach mitzvah lo lomar davar sheino nishma. It is a chillul hashem to do so, especially if you yourself don’t understand it. If you can’t explain it in keeping with darchei noam, then better first figure out pshat before hitting someone over the head with it.