I think they are dodging unclear legal issues surrounding certain steps of the model-building process while being as open as possible with the components given that constraint, allowing downstream users to make their own legal risk vs. effort choices.

Given the hardware/energy need to train it be nice, to have a legal document that said something like this model has no warranty, it may be a break through machine or a hand grenade. Use at you own risk!

Yes, this.

From what I can tell they're fine-tuning EleutherAI's GPT-J.

Alpaca was made to fine-tune LLaMa, however they also released their dataset they used to do this, and it looks like Dolly is this dataset applied to GPT-J, and does not use LLaMa itself.