Wow, that is so weird. My wife had the same issue 2 years ago, she's Korean citizen, but even she had to show up in person at a police station in Korea, not even her mother with an authorized power of attorney would get it. It seems that the problem is not only with CIC, requesting docs that can't be obtained, but that might be a case for international law; Koreans can get police certificates in most countries in the world that they have lived in without much fuss - so if there are bilateral agreements it should be the same for foreign nationals in Korea.