Does it matter? The presence of an office full of people in china means that there is an office full of people that can be exploited and controlled by the Chinese government.
Also, until recently they employed moderators in china, who by definition have access to customer data. So yes, the Chinese offices have/had access to customer data.
Many globally operating software companies have offices full of people in China, but presumably they have access controls in place to minimize the risk of data exfiltration.
On the other hand, many of the same companies have been involved in scandals where employees abused their position to stalk people or whatever, so maybe their access controls aren't actually that strict.
So it would've been interesting to hear about TikTok's internal security culture.
I'm not sure whether I'd call what moderators get "access to customer data", since it's not like they're in control, right? And aren't the posts they're moderating usually public anyway?
Also, until recently they employed moderators in china, who by definition have access to customer data. So yes, the Chinese offices have/had access to customer data.