Offensive Zombie?

What is this country coming to? My family and I decorate our front yard every Halloween. For the past three years, one of our props has been a zombie hanging from a tree. It has old clothes, grey hands and a mask that is beige tone with blood.
People seem to like it since they take pictures and wave as they go by. Last night we received an anonymous letter from an "African American neighbor" that finds it offensive. They included pictures of lynchings. They compared our zombie to black folks being hung.
Our zombie in no way resembles a black person. It is evidently clear that it is a zombie. Next to it on the ground is another one with a skeleton head. The anonymous person asked us to take it down.
Now, non of our close neighbors have had any issue with this, no one at all has had an issue with it. What is going on? I could understand if parents said that it was too scary for the kids, but my 5 yr old daughter loves it. By the way, how about if my daughter would have seen these inflammatory pictures left? I find it a disgrace and refuse to take it down.