Wouldn't a strict volume check be better in general? If I'm physically closer to one HomePod but something is in the way, obscuring audio, then I probably want to talk to the HomePod that's further away but unobscured. Or to put it another way, if I'm standing in my living room next to the door to the Office, the Office HomePod might be physically closer, but I'm probably trying to talk to the Living Room one.