That's a fun thought exercise!
I'd opt for saturation. Publish the message in as many places as possible, so that removing it from everywhere will be impossible. Automatically broadcast it to anything that remotely resembles a platform. Share it as podcasts, reddit comments, github repos, Huggingface models, pypi packages, Pinterest photos, Telegram messages, Tiktok videos. Spread it across multiple countries that ignore each other's takedown requests. Make sure it's picked up, cached and rebroadcast by everything from spammy content farms to web crawlers to The Internet Archive. Then spread it across protocols from IPFS to Tor and bittorent and Gemini. Make so many copies that you lose track of them.
Make sure to sign every copy, to prevent the other side from introducing fakes and fighting saturation with saturation.