It just so happens that Jock HAS done some very high quality work that isnt nudes. His work on school children of Ireland comes to mind, and its pretty damn good.
As to whether the lab tech was deciding that Sturges work was pornographic, since I cant read his mind I'll give him the benefit of the doubt (whether he deserves it or not). Perhaps the tech didnt have the benefit of seeing it in the context of Sturges body of work. Perhaps he didnt know whether the photographer was taking advantage of children or not and decided not to take the chance.