It is worth noting that Kurtz used the phrase "one of the malware samples", implying that there are others and that additional attack vectors may be involved. There is a fair chance that Internet Explorer is not alone in enabling the attacks.
The main thing to keep in mind is that these attacks go beyond Internet Explorer and that simply switching browsers is not an adequate defense. Kurtz sums it up on his blog "The world has changed. Everyone's threat model now needs to be adapted to the new reality of these advanced persistent threats. In addition to worrying about Eastern European cybercriminals trying to siphon off credit card databases, you have to focus on protecting all of your core intellectual property, private non-financial customer information and anything else of intangible value."
The decision doesn't have to be logical; it was unanimous.