You're overestimating the loss of fungibility. When someone decides to stop rewarding a polluter, they'll broadcast that fact to the public. They can limit that

You're overestimating the loss of fungibility. When someone decides to stop rewarding a polluter, they'll broadcast that fact to the public. They can limit that to future rewards rather than past rewards. It would be rare for money you hold to suddenly become worthless. I agree that no one wants that, which is why I don't think large swathes of society would do something they don't want. It could happen, though. This isn't about making a choice for the greater good. Choosing a currency that lets you decide who to reward gives you power. People like power. They will grab it.