Would you then claim that there was any significant doubt as to the guilt of John Gacy, Theodore Bundy, Edmund Kemper, Gary Ridgeway, John Geoghan, et al.? Would you agree that they would have all posed a significant risk of future harms had they managed to escape?
No proof is 100% absolute; there is always the possibility of some error. Video evidence? Could be tampered with. Eyewitnesses? Memory is fallible. DNA? Must be from someone with near identical DNA. Confession? Those are very frequently coerced (and, seriously, confessions are a pretty terrible way of determining guilt, esp. when there’s no forensic or corroborating evidence). 29 bodies or people you were last seen with found in the crawlspace of your home with your DNA and fingerprints on them? Pure coincidence, it’s too good to be true, must be planted.
Given that it’s impossible to know a thing with absolute certainty, how good does the evidence have to be before you would admit that there was not a significant chance of a false positive?