You are going overboard with concerns about parasites.The cost of good quality feed rations are expensive and the time is limited for most folks who are still working. Birds that range pick up insects, seed, grasses, etc., so I don't see the point of ordering worms to farm yourself for an extra protein source, unless one has plenty of extra time on their hands. Boosting the protein levels can be achieved with dietary additions of buttermilk, canned fish, fish meal, game bird crumbles, or a starter/grower mixed in to laying rations. None of those previously mentioned are possible vectors for internal parasites.
Meal worms are raised in house or bought dried. Seems much safer to me.
I use mealworms that are reared in very biosecure commercial operations. Rearing from such stock or even wild caught beetles present minimal health risk to birds. Additionally, the larvae are expensive while with minimal effort you can rear a highly palatable protein source that for some promotes enjoyment of their birds. Look into how the insects are cultured before passing judgement on whether they are worth effort or not.