sheesh.
It’s the way our legal system works, and not a reflection of an obvious truth.
No one is “guilty” of a crime until convicted.
They all do that -- the logic is considered innocent until proven guilty, i.e., he's not "the gunman" until a court says he is! (Though some go too far IMO and refer, e.g., to "the alleged suspect"!)
It's been that way a long time -- there's a piece by Mark Twain, in his journalism days, who was scolded by an editor for not including "alleged" where the editor felt it appropriate. He retaliated by writing up a garden club meeting or some such, using "alleged" or a synonym wherever he could stick it, including a reference to the membership as "the alleged ladies"! ;-)