TL;DR, IIUC:

-The May 15 BCH hard fork made unspendable coins spendable again, allowing miners to claim them.
-When an unknown miner claimed these coins, the https://t.co/2sGfitTsv8 & https://t.co/nNx0VzRrHA pools coordinated 51%-attack, to return coins to original owners.

🤯🤦‍♂️ https://t.co/LjxzYuPniZ

— Aaron van Wirdum 🎗️ (@AaronvanW) May 24, 2019