I'm wondering if she thought it might make a nice "silky". Make him something else, and edge it with satin, or some of the blocks satin.
A nice quilt throw (for gentle use) could be made from the silk dress. I would consider covering each section of silk dress used with tulle now, as you make the quilt, rather than as a proventive later, so as it disentigrates it is held together/ protected.