The issue (i think) is that the animation is done post-rasterizing. So a translate of integer pixels is fine, but scale? Skew? Suddenly you have really visible colour fringing appearing out of nowhere.

>the animation is done post-rasterizing.

The article is talking about "rerasterize the glyphs in their new location", which means it's rasterizing post animation. I think he's implying that there is something unstable with his each pixel is treated that breaks the illusion.