I think so. Based on the links posted by @NicoleIsEnough and @Shadowlauch and the context, I think your instinct is correct, but I think it’s important to realize the contrast that the phrase is emphasizing here.
Hirai says, “In other words, he chose his job (over you).”, and about her comment, the text notes: 「平井は二美子の顔も見ずにサラリと核心をついた。」; Roughly: Hirai cut straight to the heart of the matter without even looking at Fumiko.
Then a few lines later, we get Kazu’s line, “In other words, you didn’t really want him to go to America.” , and the text further notes: 「数も数で核心をついた返事をした」; roughly: Kazu also cut to the heart of the matter in her own way with her reply.
Notice how the author used the same phrase (核心をつく) in each line. In other words, Kazu and Hirai were both direct in pointing out what they were reading between the lines in Fumiko’s story, but where Hirai was pretty rude in her frankness, Kazu by contrast was frank in her own way, which was nowhere near as abrasive. That’s what I get out of the 数は数で