Others can correct me if I'm wrong, but PLA the plastic itself is food safe. As in, you can put it in your mouth and it's fine. The issue comes from the 3d printing process which tends to create small pockets and porous surfaces where microbes can hide and grow once it gets wet.
I think an insert for cutlery would be fine since you aren't going to be getting it wet and later putting it in contact with your mouth or food.