I get the feeling they are just disappointed in where liberalism has shifted and their recent work is calling out that discomfort.

My reading of both is quite honestly the exact opposite of what you describe, they tend to call out the authoritarianism they see no matter the side. Frankly even Taibbi’s recent foray into Government and Twitter is more an indictment of a government’s overreach into controlling speech which is very authoritarian in action. That series spoke about both Trump and Biden’s administrations attempting to control public discourse. It certainly feels like it was more critical to the Biden admin, and that might help the GOP…but that might be because there was a lot more evidence of it provided to him.

I think Greenwald started his rightward journey with "the enemy of my enemy is my friend", or at least, an acceptance of the fact that right-wing media were the only people willing to platform him criticizing the centrist consensus, even when he was still criticizing it from the left. But over time he's been so love-bombed by right-wing media that he's actually switched sides.

I disagree about a lot of the rest of what you say, but I think you're on point with regard to Taibbi and Greenwald.

What is your definition of fascism?

Lol. Yes and Noam Chomsky too. All fascists. /s