It's as expected, but Derek is still relieved to hear it. It's not his fight and it's only tangentially his concern: all the same, he doesn't like the idea of needless fighting.

Still, Abigail's sudden passion for the cause makes him wonder - he doubts she's become so invested, when compared to her indecision at the ball, over so little activity. But he's not about to ask.

On the other hand:

"Enfield will probably be next on their list." That's where her family originated, right? Look at him, helping out.