Now, I agree that in a general sense capital punishment is not worth the risk of wrongful convictions. No law system is perfect and people make mistakes.
But impossible is a strong word, and it is not in fact impossible to be perfectly certain that someone committed the crimes they're accused of. There are plenty examples of monsters that we can say with absolute certainty are guilty of their crimes. Some even admitting they're proud of what they've done and would do it again. I'm not going to name names because frankly I don't believe they deserve to be named, but I'm sure you can think of a few too.
However, opening up the death penalty to these most extreme cases also opens the door to wrongful convictions, and when we look at the big picture that doesn't seem worth the risk.
Chill dude, all it means is that it is a) free to claim, and b) you get to keep it as in you don't just get to trial it for a weekend which is commonly seen with "free weekends" on steam.