Killing Daken simply for being "a rapist, a murderer, and an all-around scumbag" would be jumping the gun - the supes are sworn to leave those to courts to adjudicate on case-by-case bases. (See also, DC's Dr. Light and the Joker.) Should Daken rise to Phoenix-level threat, then lethal force would be appropriate to consider.
Wolverine had no problem with chasing Mystique all over the desert before gutting her and leaving her to die, and I don't think she was a Phoenix-level threat.