MP did not seek or get legal advice. What I am saying is that if you want to get it right, do your homework, and then seek a professional vs. do your homework and then check out what a financial blogger wrote.
If you went and paid for advice, you would actually get real advice that you could use, and would be much more helpful than the 3 sentences MP managed to squeeze* out of this so-called lawyer. It seems that all MP did was leverage the fact that he writes a blog to get on the phone with a person who usually charges quite a lot for his time. There is nothing in the blog post that shows that the conclusions MP led himself to believe, would in any small way ever be binding, or to have been in reliance with the person he spoke to.
Every situation is different, and there are obviously additional rules that can come into effect. I.e. wealth taxes, the treatment of forced heirship in Switzerland, and issues relating to whether property owned by married couples will be treated separately or together under the law - a countless dozen or more that I won’t mention here.
We are talking about US law here, not Swiss law, so your question about writing to the tax office and receiving a letter is moot. If you own US securities, you invest at the pleasure of the US government and have to play by their rules.