Could exoplanets support life that has a different chemical composition? Absent details about the composition, who knows?
Why do they keep funding it? Same reason we fund evolutionary biology.
Please understand that this is the best they’ve got.
A far more effective materialist response to fine-tuning is the “Copernican” Principle (though Copernicus would have rejected it), sometimes called the Principle of Mediocrity.
He has a superb essay in the Huffington Post titled "Are We Observing Extraterrestrial Intelligence Without Realizing It?"