Bitcointalk.org is not subject to Hong Kong / China jurisdiction, so would not be required to produce data in any case. If some police wants data without a subpoena, they have to convince me that a non-victimless crime (eg. scamming) probably occurred. I certainly wouldn't help them if it looks like they're going after political enemies.

But if you're in Hong Kong or other dangerous places and you're worried about this, then you shouldn't trust anyone to protect you: not me, not anyone. Use Tor everywhere, and on bitcointalk.org practice the privacy-enhancing measures mentioned on the privacy page.