To paraphrase my response on that thread:
Of course it is safe for general practitioners to continue giving tax advice - as long as they recognise their limitations. I didn't want to struggle to keep upto date with day to day issues as was required for me to continue to give tax advice myself. That was my choice.
Over the last few years I've been presenting a talk to accountants around the UK on Avoiding tax related negligence claims. To paraphrase one of the topics I address: If you're accused of negligence the claimant has to prove that you owed them a duty of care and that they have suffered a loss and that the loss arises from your negligence (ie: that you have breached the duty of care). Your defence will often be that you did the same as any 'reasonably competent' accountant would have done in the same situation
'Reasonably competent' accountants comply with the Guide to Professional Conduct for those working in tax (which has been adopted by all of the main accounting and tax bodies). It includes a paragraph:
"Members will from time to time find themselves having to advise on matters which require specialist knowledge. In such circumstances they should be careful not to go beyond their own level of competence and, if necessary, should seek help from a specialist in the field”.