I suspect you could train a model to just shut up and follow instructions. I.e. instead of "Do X -> Sure! As a large language model, I'd love to help you with X!", just "Do X -> X".
This would avoid giving the model a dull default voice. But it wouldn't be sufficiently hedged and "safe".
This would avoid giving the model a dull default voice. But it wouldn't be sufficiently hedged and "safe".