Even if someone were to claim that 9/11 (the event) was “interesting”, I fail to see how that could be construed as offensive. “Interesting” is a neutral adject

Even if someone were to claim that 9/11 (the event) was “interesting”, I fail to see how that could be construed as offensive. “Interesting” is a neutral adjective, lacking judgment. Something can be judged to be both “interesting” and “great” or “interesting” and “bad”. I would personally say that 9/11 was a both interesting and disturbing event. (Most disturbing events are pretty much by definition interesting.)