Ok, I will bite.

What does detaining someone over an unlawful (per the written law) protest have anything to do with corruption?

Corruption involves bribes, selective enforcement of the law, unethical favoritism when it comes to legal decisions, "favors", etc.

Your links just describe people participating in a protest that was against the law on the books, and then that law being enforced upon them. You can call that specific law unfair, undemocratic, authoritarian, etc., but what's the corruption angle here?