China has access to the ISP info, they don't need to collect it from Steemit INC, they collected all of it as you sent it out from your computer. A special bot placed it in a record under your IP and mapped it to your personal use profile.
Unless you took precautions during the sign up process, you're already boned if you say anything that causes trouble.
Well I use the best stealth VPN there is that should take actions against it, and this new laptop I've avoided installing any Chinese software but yeah, I'm sure they've wriggled their way in at this point... Sigh