He's fitting a curve to existing data. There's nothing special about it and you can't draw any conclusions from it.

Any exponential growth curve can be approximated with a quadratic function.

It's similar to those pictures tracking hurricane paths, and the prediction of its path fairly narrow at the start but then it fans out further ahead in time. This is the exact same case. https://images.theconversation.com/files/82984/original/image-20150526-24769-uldufc.GIF

What this means is, in a few days the cases and deaths will start straying further away from his curve. It might show lower or more infections. It's likely going to quickly increase significantly as we're witnessing the initial phases of exponential growth.