He stalls out momentarily in confusion. What counts as hurting himself. He really and honestly doesn't know and can't imagine what it could even be.

He rallies a beat later by focusing on the last bit. "Not just for you. If I stay dead. Steve probably dies, too. We were on that helicarrier together." And he's still having a hard time adjusting to the idea of it maybe being a different Steve Rogers than the one on board, but even if it is, he still can't just let him die.