I don't think it truly qualifies as an expert system because, to the best I can determine from this limited article, it doesn't make any inferences from a base

I don't think it truly qualifies as an expert system because, to the best I can determine from this limited article, it doesn't make any inferences from a base set of rules. Rather, it is provided with a comprehensive set of all rules, and attempts to find the best solution that satisfy those rules (or, in the language of operations research, constraints). The value provided then is that, because it can consider the space of solutions efficiently, it may discover solutions which are not obvious to human operators. The way these systems are made, and as the article mentions, is that the obvious rules are added, and solutions evaluated. Experience humans will then usually discover something about the solution that is impossible/impractical, but was not included in the provided rules. The new rules/constraints, and the process repeats until humans are comfortable with the feasibility of the solution/schedule.