Why would you even mention that to the front desk? Not to mention making the smart-ass remark about leaving a dead body in there.
Do not disturb means do not disturb. If you are paying for the room, hotel staff are trained to honor that strictly so they don't walk in on somebody having sex or maybe some guy who just wants to be left alone for a couple days.
I bet you would feel violated if they went in to clean the room regardless of the sign.
Yes, I generally agree. This is the type of passive-aggressive guest that creates stories for hotel/motel staff to dine out on.
It was not as melodramatic as you think. it was actually a pleasant conversation and an education (for me) on the sanctity of the "do not disturb" sign.