There is no right, but there is a freedom? Merely because you can’t go back and punish dead people? But what about prior to the attempt, and why assume the attempt is successful? The significance of suicide law is not only what happens after you attempt it.
Suicide being illegal grants authorities wide preventive discretion, so that cops can lay siege to your house if someone so much as thinks you’re at risk. Probability of it happening also opens up unlimited tertiary possibilities. There’s the obvious immediate concerns of psychiatric holds and commitments. But there’s so much more.
Think of the publication of supposedly confidential medical information promised under Obamacare. Let’s say you blab about suicidal thoughts to your therapist, or even hint at it with general practitioners. The state can find out, and that’s a crime you were contemplating. Is that sufficient grounds to deny a gun permit? Why not, if they can ban guns for looking scary.
This is all not to mention what becomes of unsuccessful suicides. There are all sorts of consequences emanating from the central insinuation of government into property ownership of yourself. It derives from the decent instinct to protect people from bad “forever choice”s. But as with everything the state does there are manifold unintended consequences.