That’s what I think every single time I see this scene. Shiv is the kind of person who is easily convinced by the last person she talks to and so is Rome. I don’t even think she was seriously against him, I think she just had some last minute anxiety. He could have used any number of tactics to get her on his side.

“Cmon Shiv, we’re the Roy’s. Are we gonna let these fucks take our company?”

“Dad would have wanted us to be killers”.

“This will advance your career - I’ll make you a C suite executive, you’ll never have that opportunity elsewhere”.

“Mattson and Tom played you for a fool, you gonna let them win?”

“Are you really gonna let Dad fuck us one last time from the grave?”

The list goes on. But in typical Ken fashion instead he basically has a small panic attack. And as siblings and family members often do, she reacts to his energy. She sees her big brother in disarray and it freaks her out too, and she changes her mind at the last second.

She probably totally regretted it like 4 hours later to be honest. In fact I’m pretty sure she regretted it the second the got in the car with Toms smug ass lol.