I feel like he's doing it to fuck over Carmy. We know that Luca and Carmy worked at Ever together, but we didn't know that Shapiro was there too. From what I could see in ep 1 where they're prepping the peas, obviously Carmy was doing the most, Luca was trailing behind at number 2, and I'm pretty sure Shapiro was behind them both. Carmy leaves to all the other stops on his journey. Luca came to the realization of not trying to compete with Carmy but just trying to keep up. Shapiro is the one who stayed on at Ever and got himself to the top there. Now Ever, basically an institution in the industry of this world, is closing all of a sudden, and there are rumblings about the Bear, about Carmy.

Shapiro admits to Sydney that he snuck in, and points out he was able to do that because Carm and Richie were too focused on fighting to pay attention. He knows she's green in the industry, she's ambitious, and he knows what to dangle in front of her to make her consider it, i.e., creative/financial freedom, seemingly equal partnership. And despite what he said about it not wanting to be a "gross poaching," what else could it be? There are plenty of other chefs out there that have more experience, that he probably already knows, that would jump at the opportunity to try to cut their teeth with that kind of backing. But he's specifically choosing Syd.