Hmm. I am not sure thats true though. Pp also only bashed Sai na...its not like virat is thinking ki kaash meri shaadi pp jaise ladki seh hui hoti. He doesn't see her as anything other than SIL now right....
I think it would hit virat equally hard no matter who said pp's lines. Even if kaku or ninad had said that" you fought against us and the whole house for this girl who is a cheater who doesn't care for you" and " she wont go because she is used to the comforts/lifestyle hete, and you are funding her education" it would have had the same impact...in fact kaku or others would have had a better body language in any scene compared to actor playing pp who is pretty hopeless in acting department. And if Sai had given back to kaku like she did to pp, audience would have not minded the "how dare you" as much as they did when it was pp. Because no matter who was in pp's place Virat was focused only on Sai. Gussa itna hai ki he would yell at her regardless. It wasnt that he was upset specifically at pp getting insulted at all, in fact pp or whoever else is the last thing on his mind, he was upset at Sai for her actions because he doesn't know the full truth yet.
I meant to say that only Pakhi's character can come up with such lines. Only she knows what to talk that will hit Virat really hard.