Without debating the whole article, I found this one excerpt to be somewhat indicative of his writing more broadly: "Unfortunately, I turned out to be right. The short explanation is that the viruses that tend to win do so because they reproduce faster. Such a virus will grow faster inside a person, and will make that person more infectious, faster. It will also kill that person faster." This is a fairly vague statem…
There is not a single part of this sentence that is actually true:
1) the Delta variant does not "reproduce faster", except perhaps in the broad sense that it (may) be more successful in a population than other strains.
2) the variant does not "grow faster inside a person". This is nonsense.
3) "will make that person more infectious, faster." Also nonsense. There's no evidence of this, nor any bioplausibility for the statement. There's limited evidence that viral loads are higher, but that isn't the same thing.
4) "it will also kill a person faster". There's no evidence of this, either.
This paragraph is exactly what's wrong with Pueyo, in a nutshell: he takes a tenable fact ("Delta is more fit in the population") and twists it in ways that sound plausible and scary to laymen, but that are absolutely not supported by science or evidence.