He’s just this guy who has a big chance of being a murderer. He is capable of deliberately planning to kill a person outside of immediate self-defence. However evil CEO A or B may be, the moral calculus isn’t hard: society as a whole comes first. Unless we’re sure he is innocent, it’s not clear he’s someone who can be left free safely. He’s a flight risk for starters.
Police parade him and his manifesto so that they have an excuse to hold him, they look competent, and they get to keep him behind bars until we know for sure one way or another, or until they can’t hold him any longer. In which case we may never know for sure until the statue of limitations had passed and if he wants to confess.
A scary possibility indeed!