China has pointed out America’s friendly attitude towards criminals that have been granted safe haven in the U.S for the sole purpose of using them as propaganda tools or (useful idiots) against countries that are considered economic competitors.
"The enemy of my enemy is my friend" is an ancient proverb which suggests that two parties can or should work together against a common enemy. In this case, the U.S enemy would be China, It's biggest competitor.
China has called out such action from the U.S Government.
Often those that criticize a country that is not in favor of the U.S are granted easy citizenship in the U.S.
Guo Wengui is supposedly wanted in China for rape and fraud. However, he was granted a Safe Passage into the U.S, presumably because of the large amount of money he was able to bring back into the U.S and ultimately use that money to finance anti-China operations.