It is nice that posters are allowed to show that symbol if they so wish, for censorship is really widespread in this nation now.
Of course, it is very sad that anyone would want to show that symbol.
That symbol is so horrible that there are no words to describe it.
Just imagine: Jewish people (and others) in the 1920s were living nice lives in the very developed nation of Germany.
Then within a few months in the 1930s, their lives were totally destroyed. Some were able to flee Europe, but many did not flee because they could not possibly imagine that their government actually wanted to pack them into freight cars and ship them off like cattle to death camps. (I bet those 100,000 Japanese Americans never dreamed that their government would ship them off to relocation camps, either).
I feel sorry for anyone who purposely wants to hurt the feelings of people living today by using that symbol.