This isn't a correct characterization of the suspicion that Intel microcode has backdoors in it. The suspicion isn't just based on distrust of authority, like flat Earth, etc, but also on the org having means, method, and opportunity to remotely modify the operation of a CPU. And it operates within the domain of the USG, who have demonstrated a keen interest in weaponizing 0-day exploits.
What better way to acquire a novel 0-day than to simply write one known only to you and distribute it from the source? This is a good plan, but it comes with a substantial risk to Intel, or any company who wishes to maintain a trust relationship with its customers.
That said, I don't think anyone doing this is stupid, and for safety they would not install microcode malware on everyone, just some. This means we will find nothing in general CPUs, and anecdotal reports finding "something" can easily be dismissed as malicious or noise.
The truly paranoid need not worry, even if the microcode is seen to be harmless, there is always the possibility that hardware you buy is interdicted, modified, and sent onward, such that your paranoia can remain intact.
In this thread, I see implications about big media controlling microcode (which doesn't seem to be impacting piracy — if anything, it's easier than ever before), about governments imminently finding backdoors and trashing an entire generation of chips, and other extreme outcomes that seem wholly out of step with reality. (Not in the "Everyone else is dumb but we few are smart" way; in the "I have not interacted with a business or government ever" way)
I'm sure the 2600 crowd will have their next "Yes but what about the *Long form* birth certificate"-style goalpost shift if there are no backdoors found.