It seems like, if Microsoft were trying to absolve themselves of responsibility for defects in their products, the thing to do would be to claim that malware is

It seems like, if Microsoft were trying to absolve themselves of responsibility for defects in their products, the thing to do would be to claim that malware is developed by third parties outside of their control, against the terms of the EULA. What Microsoft is actually doing seems a lot more like taking responsibility. They're cleaning up the mess and helping people when they don't really have a legal requirement to do so.