if they start saying things that are too radical for liberals then they’re just going to be cancelled. So, they speak out tepidly hoping that will make some difference.

As I recall, this was a concern going back to the late 80s, when the first waves of international attention to the problem were getting started. Some climate scientists thought that if they made too dire of predictions and called for too drastic of action they would get essentially written off as cranks. The communication strategy they tried didn't work, of course, but that doesn't mean a more radical communication strategy would have succeeded. The world's economy literally and financially is deeply enmeshed with fossil fuels -- it was always going to be a herculean task to change that.