China Telecom is a global transit provider. As a sibling commenter mentioned, the document doesn't show that traffic actually went to China, just that China Telecom was an available path -- even assuming traffic transited their network, it's unreasonable to assume it actually transited through China without a traceroute at least; if the traffic did transit their network, it could be logged and sent wherever, of course. Since the routes were reported as being available for several months, the most likely explanation is that at least one the organizations' ISPs had China Telecom as a transit provider or peer, or the ISPs' transit providers had China Telecom as a provider or peer (etc). It's not an unreasonable provider to get traffic from west coast North America to east coast Asia.
It's also not unreasonable to go through Hong Kong, instead of direct to South Korea --- Hong Kong and South Korea are well connected to each other, and I believe Hong Kong has more connectivity to the US than South Korea does (I could be wrong/out of date).
Most of the non-US based global transit providers have a significant presence in US PoPs as well, because good connectivity to the US is a very important part of their business. Some of these are Telefonica, Telia, Tata. (Apparently, it's important to start your name with a T).