Maybe his intentions were not to "just focus on the evals". Maybe he wanted to, oh, I don't know:

1) show that cheating is a lot more widespread than we think

2) describe several reasons why simply pursuing and punishing cheaters is a bad strategy

3) use that to point out that we need a better solution (such as designing better evals, perhaps, but it's not the only option)

I mean, he know best what his intentions were, but that's my interpretation of his posts, both of them, taken together.

But I agree with you, it was evidently poor judgment on his part to "mix up too many issues", since most of his readers can't be bothered to try to separate them ;)