Several readers above (including myself) come to the same conclusion that the author is conflating communion with full theosis at several points in the article.
Is this an error on the part of the readers, or the writer?
If several people in a room hear you say something you didn't intend, it doesn't indicate that you believe what they heard, but it may mean you could have communicated your thoughts a little more clearly so people aren't easily left with false impressions.
I personally think what Ratzinger wrote is mostly pretty good, but it would be much better if he had qualified his statements more clearly to contrast this (partial, progressive) transformation with a complete one. At no point in the article does Ratzinger firmly emphasize that this transformation is partial, or a gradual progression. Several statements leave the reader with the opposite impression.
I don't think for a second that Ratzinger believes communion brings us to full theosis -- but I think his writing unfortunately leaves the reader with some false impressions and ideas. It is important to express these things very clearly, to avoid confusion.
It just needs to be cleaned up a little. With more clear qualifications of his statements, it would be in the same spirit of as the writings of the holy fathers.
Maybe one explanation for the different reactions is whereas others might not be so, I am familiar with Card Ratzinger's writings, know them to be orthodox and share the same principles upon which this piece is premised.