Where was the press conference? If it was in South Korea, what were the Chinese doing there?
And if the press conference was being held in China, what were the South Koreans doing there?
They were on a fact-finding tour about N. Korean refugees and organizations operating in China to help the refugees. After finishing first part of their tour, they were to hold a news conference in Beijing on N. Korean refugee situation, which was bound to be unflattering and draw a lot of international media attention.
The attempt to hold the press conference was in itself a form of protest against Chinese government. It was a success, I would say. It drew intended international media attention. It painted Chinese in a really bad light.