I downloaded the MaxMind databases and looked up the IP we were focusing on last night. The numeric code associated with that IP block is cross referenced to HK country code, but it it listed in a file called CN. So it seems like even though the geo IP data is correct (HK) it's being lumped into the China file. There are other non-China IP blocks in there too from various countries.
Not sure why that one user had the DNS issues, may have been an anomaly. I guess it's possible their HK nameservers were blocked from getting the DNS update from the authoritative nameserver (the one in Glendale) but I don't know where the block was put in place or the relationship between the ISP, hosting provider, DNS provider.