Years of training.
Good point. (Remind me, have you read Dune?)

From both of them, though the Doctor wouldn’t want to think it was also partly his fault. And yet…
Oh, nice one. And the Seeker would definitely adhere to that world view.

– Love not-yet-Jack not recognizing the TARDIS…
It's both fun and frustrating to have to describe stuff YET AGAIN. Am glad you like it, rather than your eyes glazing over.

– Ouch. Yes, technically true. Also technically true that they’ve just killed all the Daleks, which is a fundamentally good thing. But… still hard to hear the Seeker call them that.
Killing Daleks is good. He has zero regrets. The fact that his friends all decided to be upset was unfortunate, but he'd not have done anything differently.

I'm reminded of this little exchange from Busman's Honeymoon:

He [Peter] worried a great deal.

"Very likely he does," said Mrs Goodacre. "You can see he's that sort. Simon's just the same if he has had to be severe with anybody. But that's men all over. They want the thing done and then, of course, they don't like the consequences. Poor dears, they can't help it. They haven't got logical minds."

The Seeker has a very logical mind. He wanted the thing done, the consequences be damned.