I think the main reason it's not a big controversy elsewhere is due to exactly what you mention - both bubbles absolutely reject anything negative about their side and absolutely accept anything negative about the opposing side. So of course one bubble won't care, or even be aware of what's going on.
I don't think many people care what he has to say
More relevant is https://www.politico.com/news/2020/10/28/trump-conspiracy-th...
Basically a bunch of Republican operatives admitting that virtually no one is buying the BS and that's it's not a useful line of attack
If you read Taibbi's article, he's not at all claiming that the emails are damaging to Biden. The headline is "With the Hunter Biden Expose, Suppression is a Bigger Scandal Than The Actual Story".
Like in my posts, he's talking about the media's and Twitter's behavior in censoring the story - not the emails themselves. Everything he says is perfectly consistent with what's said in the Politico article you linked.
Taibbi is one of the most reputable, high-integrity, rational, and truth-seeking journalists working today, in my opinion. Reality often sits between a gray area of poles.
Maybe in the Republican bubble. Outside of it, no one really cares and sees it as a weird and poorly executed complot