The conspiracy here seems to refer to the accusation that Google is trying to actively make their search results worse, in order to force people to buy ads.
That post does seem to be paying lip service to actual benefits for users (such as speed), but then ... suddenly ignore them in favour of a Trojan horse metaphor that doesn't make much sense to me.
It would be hard to prove Google is purposefully making the organics lower quality. On the other hand, it's obvious they are shifting them down the page over time, which has a similar effect.
As for the Trojan horse metaphor, it is my opinion that's what AMP is. It's tricking publishers into ceding control of their websites. I suspect Google will, over time, leverage AMP to further march towards a walled garden. It is, though, an opinion. Hard for me to "prove" something I'm not privy to.
No, I'm not implying they're purely anything. As most of these things go, they're a mix of both business convenience and someone pushing to fix a problem they perceive on the web. Your post took into account only one dimension of an issue.
That post does seem to be paying lip service to actual benefits for users (such as speed), but then ... suddenly ignore them in favour of a Trojan horse metaphor that doesn't make much sense to me.