As a "government plan reviewer" with 30+ years of engineering experience, perhaps I can give you a little insight into this situation. I work for the Department of Defense, so I am charged with insuring taxpayer dollars are spent wisely (these days, that means getting more with less, so we are very sensitive to how much things cost). Our office acts as the regional building department to insure code compliance but also checks designs for cost and technical adequacy. Most of the time, I let the A/E decide what structural system to use for a building. However, there are times when I feel a certain detail may incure more cost than necessary and I will recommend the A/E consider other options. Ultimately, we only care about the bottom line and the structural engineer of record is usually a subcontractor, so we put the burden of cost control on the prime contractor (usually an architectural firm). If they can keep within the programmed amount of the project and still use the more expensive structural system, then so be it. Sometimes there are other factors that come into play which may warrant a different type of design. Maintenance is one of those factors.
My recommendation would be to meet with the reviewer and discuss why you chose the structural system that you're using. Keep in mind that government organizations responsible for managing other peoples money (taxpayer) usually want designs that just meet the code requirements so that they are maximizing the use of funds. A little extra factor of safety on your part does not give them a warm fuzzy (unless you can justify it).