I'm a little confused about this part. Does the Online Safety Act create personal liabilities for site operators (EDIT: to clarify: would a corporation not be sufficient protection)? Or are they referring to harassment they'd receive from disgruntled users?
Also, this is the first I've heard of Microcosm. It looks like some nice forum software and one I maybe would've considered for future projects. Shame to see it go.
This seems very plausible to me, given what they and other moderators have said about the lengths some people will go to online when they feel antagonised.
The example of "medium risk" for CSAM urls is a site with 8M users that has actively had CSAM shared on it before multiple times, been told this by multiple international organisations and has no checking on the content. It's a medium risk of it happening again.