Everything is confusing if you pretend to be an idiot.
The teaching experience I've had running through how to use applications is almost exactly the same as here. (Though I must say that this is on IO6). Simple things like the way you 'Add' or 'Edit' something being inconsistent really do throw her off. I'm sure anyone who has guided very none-technical people through using technology can relate. It's nothing to do with being 'an idiot'.
There are plenty of older people who take a lot longer to pick up technology like this, and it's also worth noting that as a demographic they are often wealthier than their younger counterparts, and a valuable customer segment.
The assertion is that the author is pretending to be an idiot in the way he is claiming the iOS7 is somehow worse than iOS6.
There are faults in iO7, but there is no evidence that it is harder for people to learn, and plenty of evidence that it is basically more usable.
There, fixed that for you.
You may not agree with the tone of the author but his point (albeit small, repeated and not explained fully) is accurate.
Far better to test, watch, measure and iterate.
The point I was trying to make is that if you're taking the view that your users need to have a significantly higher than average the level of knowledge in a domain area (i.e. equivalent to the knowledge of the domain area that the product designer has), you're going to end up with an un-usable product for the left end of the bell curve of your user population.
That left end of the bell curve is relative (as you point out) to your user population, but exists nonetheless - an "idiot" radiological engineer is not an idiot in relation to the general population, but is one in relation to the 99th percentile best radiological engineer (and, hopefully, in relation to the radiological engineer building your product).
What I was trying to say is that a well-designed UX requires that the 1% "idiot" of your target user population still knows what to do...
There are many valid complaints that may annoy designers and may initially confuse people, but in reality in really shouldn't take more than a couple of minutes to get oriented with even the most confusing UI changes.
Now the article did seem to be coming from a place of "I have never seen a computer, phone or tablet before in my life how does this work?"