V is so casual about injuring Sai, violating Sai's space. Whereas Sai even in her pain, betrayal, anger and faced with the man who imprisoned her unlawfully shows basic decency and insaaniyat and immediately reflexly apologizes for injuring him unintentionally. Thats the difference in their core personalities and character.
He is clearly getting an ego boost and sadistic pleasure in freaking Sai out because he thinks of it as "revenge". He could have allowed Sai to listen to what he was saying to Savi rather than the stunts he pulled but he wanted to be spiteful. He looks so arrogant and smug when Sai breathes a sigh of relief that Savi doesnt know the "real" truth and only a version of it.
If he really wanted to co-parent Savi and was cognizant of Sai's importance in Savi's life he would have discussed his plan with Sai instead of doing things himself.
He is taking her completely for granted even though she is his child's mother.
How can he not even apologize with sincerity- even if he feels like Sai "deserves" punishment, it was Savi who was distraught and he saw that child crying and terrified. Yet he didnt do anything and felt that he will distract her with materialistic things and even went as far as to say Savi will like space in her tent and life for P too. if nothing he should have had some sincerity while apologizing to Sai because he HURT Savi by imprisoning Sai on false charges. and he didnt even fix it. Sai ran away and he was put in a position where he couldnt reveal his deeds to Savi- varna Sai would still be in custody.