Isn't that differ nce enough for two engineers? They could certainly get more done in addition to the cost cutting. Seems like an easy case to the biz team.
This assumes that you can hire the two extra engineers. In all likelihood, their business is constrained by the speed that new people can be recruited, vetted, and onboarded. This means that even with infinite budget every engineer is a precious resource and should be allocated to higher-value projects.