If a curriculum, like KA, is "aligned" to a set of standards, like the Common Core standards, it means that the standards accurately describe what the curriculum teaches. Often, as is the case with the Common Core State Standards, the standards do not address how the items of a particular content standard is taught, preferring to leave such things up to the professional judgement of the curriculum designers. So the Common Core doesn't mandate a "style, tone, or technique." And defining "alignment" as talking about a topic at the same time as other teachers in a certain order is perfectly reasonable. You can even assess a student on that topic any way you want. But don't forget that the ways we assess students also teach them what we care about and what "doing mathematics" means.
One thing that is a big change from most states' previous standard, is that the Common Core includes 8 Mathematical Practice standards--ways that we want students to think about and do mathematics. These are things like: don't give up when solving problems, know and use the right mathematical tools for the right job, be precise, make and critique arguments, and pay attention to patterns. As with everything we learn, students learn to engage in these behaviors by practicing them, and they get practice by engaging in tasks and interactions that require them to draw conclusions, cite evidence, and apply concepts to solve non-routine problems. In a traditional classroom, these standards of mathematical practices should be woven in with all of the lessons that we teach, and we should assess students on their learning on these standards as well as the content standards.
While the Common Core might facilitate an expansion of standardized testing by giving a common set of expectations to assess, many people erroneously conflate the standards with the assessment of the standards. This is understandable --Meyer does not seem to spend any time on drawing the distinction. The CCSS doesn't mandate or recommend any particular test. And while it makes sense to speak of assessment of the Common Core, it doesn't make sense to speak of the Common Core assessment.
Having said that, any tool that claims to assess the Common Core should also assess these mathematical practices. One such tool is the Smarter Balance Assessment Consortium's test. Meyer claims that KA doesn't prepare students to be successful on the SBAC test, because students spend most of their interactions with Kahn Academy doing exercises and problems that do not require the depth that the Common Core calls for. This assertion seems supported by his data.
You may be right that KA represents the current local maximum for computerized delivery of mathematics, but Meyer is evaluating KA as a curriculum, not as a resource for kids who need extra help. In this role, Meyer's data indicates that KA's interactions with students falls short of depth of knowledge required by other assessments of the Common Core. His hypothesis that KA focuses on these types of questions because they are easier to be scored by a computer seems pretty reasonable to me. I don't think it is trash talking KA to evaluate the product it delivers against the claims they make for that product.
Finally, suppose KA found a great way to have students engage in higher order thinking skills: maybe require students to explain their thinking or make conjectures or solve multi-step problems that require them to apply concepts in non-standard ways. I don't think this would make it useless for kids who use it for extra help, do you?