Depending on the mechanics of passport cancellation it could have been both, that is the US could have issued a cancelation order while he was still in HK but HK either did not act on it in time or refused to honor it like it did with Snowden's arrest warrant. The fact that Russia did honor the passport cancellation and did not issue him an alternative travel document is more suggestive but would have been the same if Russia just wanted to hang on to him for the simple reasons of being Russia.