I haven't read the paper, so it's possible that one or both of the reviewers were way off base. But it's also possible that both reviewers were "correct". Often, when you get conflicting advice like that it's a sign that you're stuck in a compromised middle position that isn't quite working for anybody. For the paper in question, the comments could probably could have been better stated as "You have some theory in the paper which is a little incomplete as it stands. To improve the paper, you could either expand upon it, or cut it, but probably not keep it as it is."