That was my original post: Silk has some constraints, but a silk worm is still an animal, a lot of proteins could be produced in it if not for the silk fixation of the company. To produce a protein and let it accumulate in the fat body, as I originally suggested is not hard at all. And silk genes could be left alone.
Alternatively a nice cost cutting measure would be to make silkworms that spin spider silk and produce a recombinant protein too. That way the silk from the cocoons and the pupae themselves could be used.