Don't need to eat is, technically, the answer Alucard was looking for anyway. He does need to ensure the capsules are present, or if they aren't, start figuring out supply lines but that's for Later Alucard. Present Alucard is focused on D, and with the comment about worry, Alucard simply shakes his head.

"That ship has sailed, I'm afraid. Come on."

Alucard doesn't start walking. He moves behind D instead, as if to nudge him forward like some kind of animal nosing at it's young. "Inside. Now."