Good points. But I think Dooku could still pretend he didn't know who this Sidious was, and then he and Obi-Wan could "discover" him together. And the information is relatively useless, which is why Dooku could get away with giving it out and not risk raising his master's ire too much once he found out. But it's still more information than they needed to give out, because I think Palpatine's cover is good enough that no reverse psychology is even needed to deflect suspicion. .....But as long as we're talking about Dooku's role in the plot, there's something that's been nagging me about it. In the EU, Dooku was pretty open with Jango about who he really was, even if he went by the name of Tyranus when he initially recruited him. And Jango is (mostly) in on the plot. So why did Jango act like he'd never heard of Sifo-Dyas, and instead give Obi-Wan the "Tyranus" name? If Jango had just been instructed to name Sifo-Dyas as his recruiter, things would have gone a lot smoother. In fact, the only way I can make sense of it is if the intent was for Dooku to have recruited Jango while in disguise and told him nothing about the plot, so that the name "Tyranus" was genuinely all Jango knew. Then it would make sense that he'd give out the name of some dude he only met once, just to get a nosy Jedi off his back.