People have been using starch for centuries with no problems. In fact,old table linens that were heavily starched, are generally in better shape than clothing of the same vintage, which was not. I'm not really sure that your source is correct. Yellowing on old textiles is often from dust and smoke. Before electricity, homes relied on burning gas-oil-kerosene for light and wood and coal for heat. Add tobacco smoke, and even modern fabrics will yellow, regardless of starching.
Starch DOES wash out, or else accumulated starch would have commercial linens stiff as boards! That is one strange theory!
I starch on the wrong side of blocks, and keep the iron temperature appropriate to minimize flaking. No problems, and no problems with bugs, either. Can I blame starch on the tiny lizards getting in the house?