metaheuristics vs exact and traditional algorithms

Recently, my friend has submitted a paper and solved a problem with an exact method. Surprisingly, a reviewer asked him why he used an exact method instead of the popular metaheuristics algorithms! We replied to the reviewer based on our knowledge as follows:

“We use metaheuristics when solving the problem is hard and when we could not evaluate the exact solution in a short time. Where the problem is easy to solve, using metaheuristics is incorrect because of an inexact solution and also spending more time. Moreover, unlike metaheuristics methods, we can do sensitivity analysis in an exact method.”

Now, the referee accepts this content providing that authors add some related references! Although I think the above reasons are true, I need some references to prove them in this special situation.