"But standards do not usually prescribe that students must spend all their time reading texts that are extremely hard for them, with no access to books that will help them learn."
As I said in the article, it was Core supporters Petrilli and Shanahan who have made the argument for frustration level text, not necessarily the Common Core standards. The way the standards are being implemented, and the fact that they do ramp up text level expectations with no research to back up that requirement, is problematic.
Fair point. I thinks he sets up a straw man (either students read easier texts without instruction or more difficult texts with instruction) and proceeds to knock it down - so I would have to agree with your criticism.