I can see both sides of the argument really.
On the one hand there were people who head hunted, it's not like Disney has made it up to insult or offend anyone. It adds a bit of drama to the story of the attraction and is done so in a humorous way. It's based on history just the same as there were pirates, and there still are pirates.
On the other hand, could somebody claim it's misrepresenting people from parts of Africa (among many other countries) implying chopping off heads is what they're famous for? I imagine a tiny minority of people could say that, but I imagine it's a tiny minority if any.
Certainly I cannot see anyone who isn't already racist, taking what Disney has done including a headhunter and have that make them look at black people differently. I also can't really see intelligent people from Africa going on the attraction and genuinely being offended by the fact that Disney has included a headhunter in the attraction? In life there always will be somebody, somewhere that will be offended by anything. For instance if we watch war films, we often see scenes where allied troops shoot unarmed Germans because they killed their friends. This certainly happened in the war however including it in the movie isn't saying every allied soldier shot every unarmed German, nor that it was all that allied troops contributed or were famous for. It's part of a historical story, included not to offend anyone from the allied countries but just because it actually happened.
For the most part, headhunting tribes have ceased to exist in the modern age. I'm sure there are outliers, but modernization and the spread of missionary works have helped to quell the need for trophies. In fact, the last major "headhunting" was US soldiers during Vietnam; perhaps we need an historical representation of American GI's scalping the Viet Cong? I mean, if you want accuracy.
Again, empathy requires that one question the "why?" of the offense. Why is someone offended by "Song of the South"? Why might someone not like the characterization of African tribes or Pacific Islanders as headhunters? Why are cowboys the heroes and Native Americans the villains? Have your ancestors been treated as savages?
Everyone assumes it's the erasure of history, but ultimately it's coming to grips with the fact that history is written by the victors, and their story has a lot of flaws.