Say it were implemented in this world and you could say anything you like (written, spoken, signed whatever) to anyone who can hear/read/see it. What kind of problems could that create and are there any ways to resolve them without limiting that absolute free speech?
Could it even create unsolvable logical errors? E.g an omnipotent god can’t create a stone too heavy for itself to lift. Maybe there are similar things with absolute free speech.
Wouldn’t that make law enforcement easier, if attacks were plotted openly?
“Hey guys, tomorrow I’m buying the illegal weapons”
So use a legal weapon instead.
That’s assuming you find the person before they do whatever they want with those weapons.