Given the economics of mass distribution, it may be cheaper to buy a 200A service panel with a main breaker then to get a 'non standard' main lug only panel
Installing a 200A subpanel would seem to make it easier to improperly load the 100A feeder, but if your demand calculation shows that 100A is sufficient, I see no problems. When the time comes for the discussion with the inspector, I'd make sure to have the demand calculation written out in detail.
As far as arguing with the inspector, I think that the only real issue that he could have is that this 200A breaker is not properly 'coordinated' with the upstream breaker. It is generally good design practise to coordinate breakers so that the breaker nearest a fault will trip. I don't believe that there is a explicit NEC requirement for coordination, and you may need to explain that coordination is not needed here
As hbiss said, if you consider this breaker simply to be a disconnect switch,