Being a foreigner that isn't even a citizen and cheering on that nation's enemy during a desperate war is the smallest brain move a man could make. It's something you do if you're either incredibly retarded or intending to commit suicide by someone else's hand. It doesn't matter whether it's in Ukraine, Russia, USA, Mexico, anywhere.
I'm surprised some people even need the explaination above.
Put yourself in the shoes of a ukrainian soldier. You've already lost an uncle and three friends in the defensive war against russia. You barely survived yourself one time. Some of your family has fled, but you have to stay and fight. Everything you do matters. If the Russians have better information it might help them bomb or infiltrate positions more effectively. You're on constant alert for spies and military attacks.
Enter chilean journalists that constantly calls your government an illegitimate regime ruled by a dictator. That takes videos and explains how certain areas are defended and posts them online. He is giving valuable propaganda for your enemy, potentially demoralizing your fellow fighters and potentially moralizing your enemy fighters. He seems fairly clueless, so you decide to clue him in. You rough him up a bit, imprison him a bit. Expose the enemy propaganda for being liars by making them believe he's dead and then after they reported his death, releasing him in house arrest.
But then he keeps doing it. Maybe next time he'll video something that gives away vital information to russian intelligence. You've learned he doesn't have the class or self control to be in house arrest. So he has to be imprisoned.
Apparently he has health complications. Surely eastern european prisons have great health care. Apparently it took a long time for a ukranian hearing to admit and agree he had lung issues. Apparently those killed him. Maybe they killed him intentionally, maybe it is the neglect of ukrainian prisons. According to JF, Gonzalo was already a dying man.
Compare it to what a journalist might face in the west when they pose a threat. Look at people like andrew breitbart, julian assange, daphne anne caruana galizia. An important thing to remember that in smaller countries, it takes less clout to be an information threat as a journalist.