Because if he'd given Rose a chance to say, "Go save her," she would have.

I actually reckon she's the one that suggested using the horse.


And he could have, I don't know, gone back to Reinette in the flipping TARDIS instead of the fireplace, so that Reinette didn't spend the rest of her life waiting for him to come back.

But then we'd have to keep her and that would have been WEIRD. "I'm the Doctor, and these two are my girlfriends and this bloke here is the boyfriend of one of my girlfriends."