1. Power corrupts. So, the State has a tendency to go overboard. As you well know.
2. Our legal traditions grant the State the power to prosecute offenses.
3. The State often prosecutes the wrong people.
4. In any criminal prosecution, the State has ALL the power.
5. Western legal tradition, starting waaaaaay back in 1215, has sought to limit that power in order to give accused people a fighting chance. In case the State has gotten it wrong. Which it often does.
You're not arguing with me. You're arguing with Magna Carta.
This particular case happened 2,000 miles away less than 24 hours ago. You and I have NO IDEA what motivated this criminal. Your confidence in his guilt as a terrorist and, I suspect, your eagerness to lock him up forever and throw away the key or, preferably, simply shoot him behind the jail, is exactly why the State needs to be forced to be fair to accused people. This guy? Sure. He's guilty of murder at the least, and he'll be in jail forever.
But if it's easy to railroad him by blithely labeling him a terrorist just because you dislike his last name, it'll be pretty easy for President Ocasio-Cortes to label you as a terrorist down the road, simply because she dislikes your lifestyle and choice of hobby.
Me, I prefer to fight the State's efforts to make themselves stronger at every turn. YMMV.