Have you considered to do a dual-world "build"?

Meaning you build the stuff in one world; while doing the boss hunting in another one.

By doing that, the only raid you will experience is the nature one which is the one prior to killing Eikthyr. I don't think that one will be shocking to your son.
But if you think it is, consider if this is actually the right game for your son to start with.

Thorin :)