Yeah, a small server endpoint which returns a blocklist of words not allowed in titles should do the trick.

When the pandemic is over, you can update the server to return an empty blocklist.

That sounds a bit risky - like if Apple finds out I'll get removed from the store altogether. I guess I might not have any other option if my appeal fails...

It’s not risky because it would require someone to use their brain to discover it. The types of people rejecting a link aggregator app for showing COVID posts is not using their brain; they’re trying to review as many updates as quickly as possible.

“Wow I saw the word covid, into the garbage bin.”

Then after the update is accepted, you can show Covid-related submissions, and then you can hire Epic's lawyers when Apple removes your app.