Her answer makes it apparent just how well she understands the game of thrones. Better than her brothers did, probably. Certainly better than her father ever had. Another result of her time in King's Landing, probably. She'd had more of it than any other member of her family, after all.

"Winter will be here soon. The sooner I can be secure in my authority there, the easier it will be to maintain it." Winter will give him plenty of time to work on gaining the loyalty of the men of the Vale. It's loyalty that he will need in the future.

"You and your brother will have Winterfell to yourselves soon enough."