Wouldn't anyone then be able to provide proof of that participant having exited? The participant would have generated a signature the moment they exit.
The point about the extra energy is potentially valid, although it would need data.
Methane being worse than CO2 doesn't change the fact that it's a cycle and thus it's not causing extra warming as long as the amount of animals is constant.
Alternative forests, etc, is equally a one off thing. Keeping the pastures doesn't make anything worse, and reverting them back would only be a one off improvement.
Binance has its own dollar based stablecoin, BUSD.