This is economic insanity. There is no amount of money that Americans can spend that will have any effect on the climate in any predictable way, because China and India are going to continue to use fossil fuels, and the Third World is going to industrialize.
Of course "deplatforming works." Fascism works. Totalitarianism works. Terrorism works. That's why people keep embracing such ideologies, even though our culture nominally considers them to be among the greatest of human evils.