On my recent trip to Singapore, I noticed the same type of sign in the metro stations, a pitcure of the Durian fruit with a red circle and slash through it.
One of the friends that I went to visit, who is Singaporian, insisted that I try a wonderful Singaporian dessert that was made with Durian, but after one whiff and one bite, I just couldn't do it, the smell was too intense as was the flavor. I think I'm pretty open to trying different types of foods like the Fruit Bat I had in Seychelles, but Durian was too much. I hope I didn't offend my host too much.