Blizzard usually investigate accounts after players reports.
Relocating from US to China, and accessing the account from there on a permanent basis should trigger only a one-time locking. as lilsavalex already mentioned, but IF GM investigate it for any reason (like player reports lol!), that China IP would ring them a bell that the account have been hacked and used from unauthorized person, so you could save your ass if get perma-banned later. But only if you appeal from USA based IP (since your battle.net country is USA)