I think it's a jerk move -- totally -- but, JB, from what you've written before about your self-absorbed ex, it's pretty much in character. Still, a totally unkind, thoughtless move.
For those who talk about kids and their social calendar and how they want to connect with their friends: you're absolutely right. But it's not about that and connecting with their friends doesn't mean disconnecting with their parents. It's about still being a parent and still being available to your almost-adult child. Even at that age, they need to know you're THERE and that there's constancy in your relationship with them, that you're willing to keep the home fires burning, so to speak, even if they just touch down and go off again, then come back and then go check in with another friend. I don't mean you should be a martyr to your kids and I do agree that our relationship with our kids evolves a great deal between16 and 25. They still need our love and our presence. Given that this 2 week break is all this kid (& her dad) get for 9 months, I don't think it's too much to ask. And the SD shouldn't have to ask. Her (obviously clueless) dad should see that.
All that being said, this does seem so totally typical of things you've posted in the past about him and hopefully SD doesn't expect much more from him. So screw him. If you have room, have her come directly to your place at the beginning of her break and stay with you until at least the 26th. Yes, she'll go visit friends and such but her home base is with you. She should always be able to count on a home with you, too. Since her dad is such a poor role model for adult relationships, I'm sure she looks to you (even if she doesn't know that yet) for an important counterpoint to his behavior.
Let him go. Focus on her.