You are absolutely correct; it isn’t a peer review scientific journal. So it is quite acceptable to put opinions forward IF it is stated that it is an opinion. If a writer states something as a fact, particularly when claiming it is a well known fact, then it helps that person’s argument to provide some evidence to back it up.
This sort of question is problematic:
There is no way to adequately meet your closed question. It would be like asking you to prove that you have never been an to the bottom of the Mariana Trench. Perhaps it would be better if you said something like ‘in my opinion, it sounds like you work for the fast food/beverage industry’. This would allow for a friendlier discussion to continue.
