Kazko - I hate your bug!
Goliath worms are Tomato Worms. They are a HUGE pest, and it would be illegal to release them - just so you know. You can buy them for pets or for your gliders, but the moths can NEVER be allowed out - nor can the worms.
Earthworms are completely different. The things we call "worms" - meal worms, Goliath worms, wax worms, silk worms - are not true worms. They are a stage of moth. (except meal worms - which are a larval stage of beetle.) They are ENTIRELY different than true earth worms. They are different structurally, nutritionally, in their diet, in their life-stage... every thing. I do not think they'd be suitable to feed. They are not even "bugs" which all the others are.