My opinion of that is entirely irrelevant in most cases. It depends on the people of the cultures he is borrowing from and their identity. Gaiman could be perfectly respectful of Norse mythology but might unintentionally have insulted or misused myths of, say, the Cherokee. What matters is if you have a cultural identity and the writer dresses it up in clownface and makes it do inappropriate acts in the name of entertainment. Let's say someone makes a story in which George Washington is a transvestite stripper and prostitute with artificial oversize buckteeth as well as a complete coward. This is just a vague feeling of mine, but I bet that at least some Americans might feel a bit uncomfortable as the rest of the (non-American) audience howls with laughter and agree what utter prats these revolutionaries were.
Understood and accepted. You couldn't have known what a massive trigger Shriver's arguments were for me.
Now that I can understand and empathise with and I apologise for completely missing your point. And there are many valid parallels. Unfortunately this is a signal to noise ratio problem, one which the Internet unfortunately tends to amplify due to the presence of trolls and attention seekers. The argument "they are just looking for reasons to be offended" is not wholly untrue, because every legitimate cause with people who are genuinely trying to deal with a problem will attract parasites who do just that.
If your argument is "please try to understand that I am doing my best and that I can stumble," I can only say that I respect that and will do my best. I am truly sorry that communication failed in this instance even if it did prove an inadvertent example of exactly what you meant.