I take Orwell's style advice (and Strunk and White's style advice) as meaning something like, "if we were to underline in red the worst writing of poor writers, and then go back trough and suggest improvements, the following suggestions would be among the most common that we would make." Note that this way of putting it is not absolute. For example, if I were to go through a paper, find the worst writing, suggest improvements, and then notice that a large fraction of my suggestions would involve switching a passive voice to active, then this would (a) probably be worth noting and worth putting in a compact style guide, and at the same time (b) not be the same as an absolute recommendation that all writers always avoid passive voice.

In short, I take the advice to avoid passive constructions in something like the following way: "if you use the passive voice, and if you're not a successful writer, there's a fair chance that you could easily improve your style. Try the active voice, compare it to your initial passive construction, and then choose the one that seems better." That may often result in a writer (one who is open to the possibility of improvement) switching from passive to active.

The advice won't make a writer into an Orwell, but it could make a poor writer into a merely mediocre writer, which is a worthwhile goal.

That Orwell violates the absolute version of his style advice doesn't negate the value of the advice, any more than the value of training wheels is negated by the fact that experienced bicyclists don't use them.

David Beaver's essay seems at times to be trying too hard to find fault with Orwell's essay. For example, the last bit about rule-breaking strikes me as silly. It's also suspiciously convenient for Beaver's own argument. After all, the statement (to "break any of these rules sooner than say anything outright barbarous") is precisely the softening of the advice that disarms Beaver's previous criticisms. For, Beaver's criticisms rely on the (superficially) absolute way in which the advice is stated. Orwell tells us for example to "never use the passive where you can use the active." The "never" makes the advice absolute, admitting no exceptions. This is critically important to Beaver's own criticism, because Beaver immediately supplies a counterexample from the very essay in which the advice appears. Disproof by counterexample only works on absolute statements - statements that allow no exceptions. If the statement had been written more softly, as advice to take special care when dealing with passive constructions, then the counterexample would have proven nothing. And so when Orwell softens his own advice by writing, "break any of these rules sooner than say anything outright barbarous", Beaver's argument is undermined. It's interesting, then, that Beaver attacks it on silly logic-chopping grounds.

However, his own political and economic ideas were hopelessly naive and muddled, and many people who lived and wrote at the same time had a much closer grip on reality, even though they are nowadays forgotten.

Prompted me to issue a respectful downvote and post a rebuttal from the man himself.