There is an analog here for what we used to do with accounts on Stack Exchange and Creative Commons, too – you pull the username and keep the content as it belongs to the community, and removing it might take something of value from the commons.
Note that Creative Commons is also the default for Discourse installs unless site operators specify differently in their ToS:
3) User Content License
User contributions are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Without limiting any of those representations or warranties, CDCK has the right (though not the obligation) to, in CDCK’s sole discretion (i) refuse or remove any content that, in CDCK’s reasonable opinion, violates any CDCK policy or is in any way harmful or objectionable, or (ii) terminate or deny access to and use of the Website to any individual or entity for any reason, in CDCK’s sole discretion. CDCK will have no obligation to provide a refund of any amounts previously paid.