The surgery was done in 1994, so the blood was probably not being tested at that time.
This is a very interesting article. The key statement for JWs is not regarding the infection, but rather the one where the wife and daughter advocated plasma over blood. Both plasma and blood are specifically prohibited by JW doctrine, and here they are advocating plasma publicly.
They can wriggle out of it a couple of ways. They could claim the paper misquoted them. Or, the could claim that since the husband was a non-believer, he made his own choice. They could claim that they couselled him not to have any blood products, and that at his insistance they suggested a component, rather than whole.