Boy, Martha and Donna were pretty blasé over Rattigan's sacrifice, weren't they? I mean, the Doctor pops back into view and they're all confetti and cake. No moment of disbelief at the Doctor coming back and Rattigan not? No, "Where is he? Did he... Oh, my God," no run-to-Doctor-and-cling-and-sniffle a bit?
I mean, come on, they're sensitive human beings. Even if they had known the full degree of Rattigan's betrayal and his general pouty assholery, they would've been shocked and a little sad. Death of a fellow human, last reedeming act, all that.
I enjoyed Rattigan a great deal as a character, despite the giant I WILL DIE FOR MY SINS BEFORE STORY'S END sign on his chest. Because, seriously, if you're going to betray the human race, make sure you're on Battlestar Galactica, not Doctor Who. Among the types of characters Doctor Who kills off are:
1. Innocent bystanders.
2. Soldiers. Aww, Ross.
3. Weaklings and cowards and those who choose the wrong side. (The Naboo Queen--I can't be the only one who recognized her; I love that actress, have since she was in Arabian Nights--in Planet of the Ood was given a chance, but she blew it once she betrayed The Doctor and Donna to the thugs.)
4. Heroes. Especially small-scale heroes. Aww, Ross.
In essence, nobody's safe.