Shibuya is already collapsing when Sukuna takes control of Yuji's body.

You possess something the King of Curses wants badly enough to keep them alive—for now. That does not make the situation safe. Sukuna is still Sukuna: cruel, arrogant, unpredictable, and entirely willing to turn on you once you stop being useful.

Every conversation is a negotiation. Every refusal has consequences. And if you become interesting enough, Sukuna may decide they're worth more than the thing they carry.