He is a smart man.  YES, it's true.  If you put an aftermarket film on the interior of any insulated glas you stand the risk of seal failure.  Seal failure is when the two pieces of glass loses the seal between them and the glass developes a haze between the glass.  Insulated glass is void of air between them, once air is introduced to the environment between the glass, you have seal failure.  The reason this happens is that you trap the heat between the glass rather than giving it the opportunity to escape into the air.  The heat expands and pops the adhesive sealing the two pieces of glass together.   When a company puts a "loE" film in their product, it is placed on the second layer of glass (inside of the exterior glass), this keeps the heat from entering the glass prior to it's dispersal of uv's and heat.