Meaning you think that was reminiscent of the original Dawnguard, and not Isran?
No, I think it is hard to say without any references to it at all. It might have been like that since the last Dawnguard or it may have been used recently. The problem is that we do not know, though, as I said, I don't think they are above torturing vampires for information. I doubt Isran would do it for fun, he seems to be a much more practical man to do that and is probably more concerned with actually fighting the vampires than fun.
As for the whole Evil thing: I don't think the Dawnguard are Evil and I don't think they are Good. They are, as far as I am concerned, a Neutral faction set to do a job, which is protecting people from and hunting vampires. The people they protect will see them as good, while the people who are hunted will see them as evil.