I guess the main danger is that the chickens may be so thorough at finding all the grubs, both mature and immature, as to decimate the colony. They also need moisture and shade, especially the small ones, so in scratching everything over and possibly exposing them to the sun more might also be a problem.
You don't need an expensive bought "pod" to raise them in. Any
bucket or barrel or other container will do, just tipped up at the right angle, and the mature grubs will crawl up the incline and drop out....perhaps to waiting chickens! Put a drain hole on the bottom corner and a loose lid over the open end to shed excess rain, but allow adults to enter and lay, and you're good to go.