The error is occurring for a website that may be blocked in the country of hosting the forum. However, this legal situation should not prevent a topic from being created given that other jurisdictions (e.g., the reader’s jurisdiction) might not block the same website.
Personally, I think this is a Bug to prevent creating a topic or posting about a censored URL. It’s not Discourse’s decision to make whether to link to a website or not, but the authorities of the viewer’s jurisdiction.
FYI, the link I’m trying to link is a report from TorrentFreak.com about a study ordered by the EU parliament regarding AI and copyright. There’s nothing illegal there: it’s just that Germany seems to have banned TorrentFreak.com, otherwise a very good source of information about Internet censorship.
So my question is: how to bypass Discourse’s code that really should be a warning, and not a block?