Nothing about what they're saying is wrong. None of it is illogical or against her wishes, technically. The planning is careful and smart, both things that she generally gets right on board with. There's even bonus points when Rodeo so swiftly dispatches Demi, revealing exactly what Adelaide herself already knows to her bones - that she is her brother's top priority.
Why, then, does the discussion make her feel boxed in, caged, claustrophobic? She's never been a rambling type, a wild thing that needs to roam free like so many of those dogs who need to live under the open sky despite all logic and poison gas clouds - but even a homebody needs space to stretch her wings, to feel free and even, sometimes, unsafe. She's starting to see that for her that means getting out, and that though her subterfuge was necessary it also was, in a lot of ways, something that she wanted. Leaving the Capitol on her own, under pretenses, and traveling out even part of the way to the Park on her own was her taste of that, her little bit of thrill-seeking, like post-apocalyptic bungee jumping.
And now when she leaves the Capitol she'll arrange her travel through her well-tailored husband, and she'll leave with escorts, to be handed over to a van full of still more escorts.
When Thomas explains his plan further, Adelaide murmurs her assent. Then as her brother starts to speak again she stands with Charlie, lifting him up to rest on her shoulder and bounce as if he's fussing, when he isn't. He presses his rosy cheek against her shoulder and closes his fist around the material of her shirt, and she paces the few steps toward the big window, and back. Restless, but not reasonably so enough that she will voice it. Walking, but still listening.