Much of the debate here is way off topic, and I'll keep out of the political side of it for now.
On the linguistic side, however, I feel obliged to make the point (as I've done before) that "Scotch" is no more than a contraction of "Scottish". A great many people, including many very well-informed Scottish people, have used, and continue to use, both words interchangeably.
It's certainly true that the word "Scotch" is fast going out of fashion except as a specific term for whisky, mist and other more-or-less inanimate objects; but it is quite wrong to state, baldly and without qualification, that it is per se incorrect or insulting to use it of people. That is a fairly modern snobbery, though one that I must confess to having believed when younger and more impressionable.
That doesn't mean that people don't sometimes use the word with the intention of insulting; but the person who takes offense and rises to the bait risks appearing just as ignorant -or more so- as does the person who made the remark (perhaps innocently) in the first place. Let's try to avoid irrelevant distractions of that sort.