That is probably a smart move on the part of your friend given the political climate. Things are very unstable within the CCP government at the moment and it is not clear which direction things may go. There are several factions duking it out for control in the top levels of the CCP. Depending on where your friend goes in China, like around Beijing, security measures have increased.

It could also be that getting back out of China could be a problem. Does your friend hold Chinese citizenship? The CCP is starting to deny exit for many people due to "security issues." Even foreign passport holders are having their exit visas denied and not given a reason why. A US citizen could end up becoming a political hostage given the current tensions if China needs a bargaining chip. They have done this before. Foreign travel by Chinese citizens is being restricted by the government. Some Chinese people have been forced to turn in their Chinese passports and don't get them back.

I also heard that for those that have dual passports and citizenship, the Chinese government will no longer allow people to hold both - you either give up one of the other. That really makes it hard for those people used to freely traveling between the US and China using both passports. Trying to function in China with only a foreign passport alone has become very difficult. That is why some people keep two passports. They use the US passport to enter and exit China and the US, while using their Chinese passports within China.

So, it is probably a wise move to stay put for right now instead of taking the risk of possibly not being able to leave China with all the turmoil taking place within the government and on the streets. It is simply too uncertain.