This does not tell us he can not lie. It just says he has no free will. But the rules that bind him might even force him to lie under some circumstances.
Uriel doesn't have NO free will. Just not much. It's an important distinction. A while back Jim answered a question about how the Fallen must have had some free will in order to rebel in the first place. I think the same applies to all beings. However, due to Uriel's nature and high position, he cannot do all that much without breaking himself and the universe (or go a bit crazy perhaps).
Can change you does not mean success is guaranteed. If you can make Harry change himself you have changed him
I think that while this view is valid enough as an argument in our world, I think in the Dresden Universe it isn't so much the case. It's a philosophical position in our world, but not in Dresden's. Jim is being clear enough that Uriel can dispense objective truth. However, you are correct in that he doesn't have to. But by choosing to lie he would effectively destroy a universe (remember what the Angel of Death in Ghost Story said about unmaking a reality by interfering)...perhaps it might even destroy a part of himself. He would Fall. Not to mention cause probably another civil war in Heaven. So you can see why he might not do that either.
Harry might not realise Mab's strategies for changing who Harry is. In point of fact, he mostly seems to as pointed out by Michael and Eb etc. Doesn't mean he doesn't plan a bit for it or try and resist. Planning to resist is part of resisting in itself.
If you are prepared to die for it. With most people torture and bribes will get you quite far. Especially if they don’t know what is happening or don’t understand. Harry changed somewhat and nearly changed a lot more if he had not gotten his act together. He is Lucky Mab’s ambitions are not as destructive as Lasciel’s who could have changed him as well.
Or again in Uriel’s interpretation it was all Harry’s free will.
Everything changes you. So Lasciel, and Mab, have succeeded in a sense. Just by interacting with Harry. But changing the core of who he is...that's another thing entirely. And neither of them have achieved that...yet. It was Harry's free will but it wasn't totally free as a Fallen was interfering. Uriel reacts strongly to that sort of thing. But Uriel doesn't really interpret much. That's the job of the Judge, in a legal sense. Uriel mostly just does his thing. He doesn't make a lot of decisions on what constitutes universal law breaking, he just sort of knows via intellectus and reacts.
She actually liked Harry’s arranged suicide in Changes. She does not mind Harry arguing with her as long as he understand doing it in public will have grave consequences. She will actually put up with a lot as long as he is a winter knight worth having. What she wants is a knight who shared her purpose, I think that is done, is becoming more and more effective, that is happening, and shared her ruthless efficiency, we will see how far that gets but he moved in her direction.
Much of that is true. But it isn't the whole truth either. Harry shares
part of her purpose but he can't share it all because he doesn't know it all.
