I think the forum should stay visible. For example, I've found out about the EEVblog forum after Google Search popped a few very good threads from EEVblog, and after heaving the nice surprise to not be coerced to register for a click on a JPG and a 20kB download.
Nobody knows yet how to deal with ChatGPT bots.

Maybe add some more human-verification tests for new accounts, or do like other forums where the first 10 posts or the first 3 days (whichever comes first) will become visible only after a moderator approval. Though, this would probably need much more than 3 moderators to cover 24/7 human approval for newcomer's posts.
Responsible moderators are hard to find. My advice would be to make generic Moderator1 .. ModeratorN accounts, and keep those separated from the current username, so the moderators can come and go without altering their presence as normal users. Otherwise, in time they'll get hard fillings.
Most of all, tell the new mods that they are
to guard against vandalism only, i.e. against chat bots, and not to establish the technical correctness of a post. If a moderator thinks it should be 2k2 and not 1k2, then use the normal username to comment about technical solutions. Mods accounts must by used for administrative tasks only.