It is convenient because the reason cannot be talked about out in the open. Hence, from a killer's perspective, he can say that and get away with it.I guess I was the first one to point out that Ashutosh can’t be a killer for reasons town will get hence I don’t get it how is it convenient
Hypothetically speaking, let's say you're indeed the killer. Now when you say something along the lines of, "Hey guys, we know he cannot be the killer because, well he said xyz which only townies will know."
That "xyz" becomes a very safe thing to say because it cannot be objectively discussed without putting the entire town at risk.
So there is a possibility that the killer can try that out as well. I don't know why this angle is being ruled out.