So this seems like a great opportunity to open a dialogue with a company you are complaining about and have direct discussion over your concerns. You could even update your article with their responses, and have a better post at the end of it all.
- Switzerland does indeed have freedom of speech and press but this does not mean that you can say "whatever you want", not to the same extent as in the US at least.
- What could follow here is either civil or criminal litigation or both. Relevant are Art. 28 ff. of the Civil Code [1] or Art. 173 of the Penal Code [2].
- However low the chance of success for Proton AG might be here, do not "open a dialogue" and do not "explain" or "justify" your arguments further, as other commenters have suggested. I cannot stress this enough, OP.
- Faced with a lawsuit, your best option by far would be to consult with a lawyer. If that is too expensive or disproportionate for such a small blog, your second best option would probably be to ignore them to see if they acutally file a lawsuit. In this case you will still have ample time to seek counsel later.
[1] https://www.fedlex.admin.ch/eli/cc/24/233_245_233/en#book_1/...
[2] https://www.fedlex.admin.ch/eli/cc/54/757_781_799/en#art_173
But I'd love to hear more rationale why it would unwise to open a dialogue? Not specific to this scenario, of course, but in general what risk does that expose?
Amendment to my original comment: It just crossed my mind that the federal law against unfair competition (UWG) could also be applicable.