They're getting blasted for causing a massive worldwide outage due to what is clearly inadequate quality control. I don't see why this is any better if it's "pushed a kernel-mode driver update with bugs in it" than if it's "released a product with buggy kernel-mode stuff that can be made to crash by an innocuous-looking data file, and then pushed a data file that made it crash". Same result either way. Same demonstration of inadequate quality control either way.

I think the story they're telling now, which so far as I know is the truth, looks worse for them, because it requires them to have screwed up their QC twice. Once when they made a product that do such bad things, and once when they pushed the data file to millions of PCs without checking what it did.

So I still don't see how "this particular file happens not to be kernel-mode code" makes them look any better, and therefore I don't see why they'd be saying it "to deflect blame". It doesn't deflect blame; they look just as bad either way.