Dumbledore found it somewhat comical that Horace had disguised himself as an armchair in a clumsy attempt to deceive him.
If a Death Eater had come, Horace's strategy might actually have fooled them.
Unfortunately, the probability of anyone coming to find Horace in the middle of the night being a Death Eater was remarkably low, a fact of which Horace himself was well aware.
Chapter 1070