Why on Earth would Wu implement this attack on the mainnet? It would likely end up killing his goose that lays golden eggs for him. With the low liquidity in the markets, he would likely only gain a small morsel of foie gras from this. Even if he tried to implement this attack on the down low, since his company is the one most likely to implement such an attack, he would be under extreme suspicion and become anathema to the community.
It would probably be more prudent from him to demonstrate that this attack is possible on a testnet. After releasing his demonstration, he would be seen as the hero; confidence in Core would be shaken; and people would likely buy up BCH and anoint it as the true bitcoin.
I suppose that it is possible that even if he demonstrated it with a testnet, the people that have swallowed the Blockstream Kool-Aid would discredit it, even if valid. Perhaps a black hat demonstration on the mainnet would be the only demonstration that would get through to them.