Elliot,

I don't know if he uses that exact phrase anywhere (and I didn't indicate that it was a quote), but the implication seems pretty clear and I thought it was fair to call it "characterizing...as immoral".

Here are some direct quotes:

Research on embryonic stem cells raises profound ethical questions, because extracting the stem cell destroys the embryo, and thus destroys its potential for life. Like a snowflake, each of these embryos is unique, with the unique genetic potential of an individual human being.

As I thought through this issue, I kept returning to two fundamental questions: First, are these frozen embryos human life, and therefore, something precious to be protected?
...
And while we must devote enormous energy to conquering disease, it is equally important that we pay attention to the moral concerns raised by the new frontier of human embryo stem cell research. Even the most noble ends do not justify any means.

Since he decided against continuing to use these means, it seems clear that he considers them to not be morally justified: immoral.

Gil