But i think that his sending Faith after Angel-with-soul in early season 3 Revelations shows that he does want Angel killed at that time.
Which still links to what Angelus had done. The first time Xander sees Angel after S2 was in the mansion where Buffy was recklessly
kissing him, knowing full well that a moment of true happiness sets Angelus free. That sight angered and scared Xander at that same time.
I think he wanted to hurt Buffy's feelings more than actually wanting to kill Angel, because when Xander found Giles knocked out on the floor, he tried to stop Faith from going after Angel telling her that Angel wasn't the one who hurt Giles. If he really wanted Angel dead, he would have lied and told Faith that it was Angel.
But then Xander implied to Buffy that Angel was the one who hurt Giles, because he wanted to hurt Buffy. Now that for me is worse than him merely wanting Angel dead. He was petty and cruel in that episode.
So the question is, when does his opinion change?
Xander had been so supportive of Buffy after Angel lost his soul "“see Phases. He'd saved his "I told you so" until one of them had died, which was understandable and easily sympathized with.
Here's a drabble by
a2zmom that shows Xander's feelings:
Xander was scared, but not worried. OK, Angel was now crazy psychopath guy, but Buffy would protect them. She always saved the day.
But instead classmates started dying. And Angel left a little present for Willow. And finally he murdered Ms. Calendar.
Through it all Buffy did nothing. Xander had read enough comics to know this was not how superheroes behaved. The more he stewed about it, the more his fear morphed into anger.
As he stepped into the library, his harsh words spewed out. If she thought she couldn't kill Angel, he'd shame her enough that she would anyway.
but he also tells the gang that he hated angel long before they did (yes, he says angel, not angelus),
Actually everybody calls him Angel in s2, no one called him Angelus, not even Buffy.
Re-ensouling him kills only angelus and leaves angel alive. In the fight for world safety, having a strong vampire with a soul fighting evil is better for the world,
I guess it shows that Xander couldn't separate Angel from Angelus at that point. Soul or no soul, it was the same guy.
It was responsible for his not liking angel in the first place (before ever knowing that he was a vampire),
Of course, Xander didn't like Angel, in the beginning, because he was jealous that Buffy liked him. He didn't like Owen and the other men Buffy was interested in because Xander liked Buffy. But then, Xander finally moved on by the end of S2 -or the beginning of S3- as he wasn't jealous of Scott and didn't care if Buffy dated him.
But i do think that he hurt Buffy by isolating her from her friends by telling that lie, especially since she was already on her way to fight and kill angelus anyway, and was ready and willing to do so (unlike during the only chance she had had previously, during innocence).
I don't think Xander wanted to isolate Buffy from them, if he did, then her leaving town wouldn't have hurt him so much.
As for Buffy killing Angel, she could have done it so many times. They already knew where Angel was -the factory- and yet Buffy did nothing. I don't think she was ready to kill him... until Passion.
But as other posters mentioned already and i repeated in my post, even if he had originally intended to give Willow's message and then changed his mind, he could have said something else
I don't think when he said "Kick his ass", he meant putting words into Willow's mouth. It was a spur of the moment, he didn't think when he said it. He said exactly what he felt. He wanted Angelus dead.