Droids were capable of a lot, and Luke was more than aware of it -- but that didn't mean that they didn't work on the programing they were given.
It didn't matter though, because even if he hadn't meant for her to get whatever she had out of that comment, Rey clearly got something and that was good. He was glad. Luke didn't much care for not having all the answers even if he was virtually the same age as Rey and her friends -- one could be as wise as one liked but life experiences were pretty important.
"It's what I'm here for. Sort of," Luke said with a wry sort of smile. Or, well, he was here to help. Anyway, it was a decent sort of distraction from his own worries, which were many at the moment. "Let me know if you find anything. Now then -- are you ready?"