I seem to recall some recent studies showing that student actually comprehend/retain more when using eReaders, which is one reason why more schools are adopting them (and why they seem to be popular with special ed teachers).
The majority of my higher education is in mathematics and computer science (though I also picked up a degree in English along the way, so I'm not a *complete* geek), and I think that biases me towards a more quantitative assessment of the author's statements. Specifically, IF the purpose of reading is to comprehend/absorb the written work, and IF eReaders are able to do that as well as physical book, THEN the claim that "eReading is not reading" seems like nothing but opinionated bollocks.
I love books and reading, adore my Kindle and have a wall of books in my living room. People who set up false dichotomies--especially about something as trivial as format--for no other reason than to look down on those on the opposite side of the line they've drawn drive me nuts.
I can't wait for his next article about how people who read paperbacks, rather than hardbacks, aren't really reading.