AAAaaa Pluto! You're the best! Sora will definitely, um, clarify that while he's not sure if a replica is supposed to be alive or dead or what, the heart he's referring to isn't the flesh and blood pumping thing. That heart and the heart he's talking about are two completely separate things! What he's thinking about is more... conceptual? Uh, that's not quite the right word. (He won't find the right word, he is not a smart guy.) Anyway, he's 10000% sure that no actual living tissue is involved in any way in the the transfer!

Sora... is going to laugh a little. Uh. Hm! Well. Basically. He's... sort of a passenger in this body? Like, if this body's the bus, and the bus driver had the wheel, he got on at some point, and him getting on started killing the bus driver? And now he has control of the bus and is trying to keep the bus driver alive while he gets a new bus. The replica is the new bus. He is multitasking! (Listen, it's the best metaphor he's got in the limited amount of time he knows he has with Pluto.)