I did do that math wrong, but to be fair, the article is comparing apples and kumquats. $26 billion is how much Gilead has in cash, which has little to do with Sovaldi at this point. $1 billion profit (let's say that's annual, rather than over the life of the drug) on an $11 billion purchase would be less than 10% annual ROI. That's very low for what was still a very risky investment (unapproved drug).
I think in the author's ideal world, the lowered profit for Gilead would mean they aren't rushing to provide Sovaldi a multi-billion dollar profit either. So the price drops well below $11 billion, and you get a solid profit margin without gouging people that need the drug.
