> is it ethical to allow a model to give medical advice, knowing that it can be wrong. Most people would say no,

I wouldn't be so sure, most people I've met seem to be all too eager to suggest what worked for them (or they have heard is supposed to work) in conversations about medical issues, so I can't really see the public generally categorizing advice or guidance being given in non-professional setting or by non-experts as unethical. The taxpayers representatives having to bear the costs of the outcomes (at the very least as reductions of tax revenue) I can see being of a different opinion though.