Honestly, the biggest problem with the study is that counties aren't reporting the same level of detail. There's no uniformity and CDC had to cull a sizeable chunk because some counties/states didn't report whether cases were hospitalized nor the ages of the patients. Oregon, for instance, is no longer reporting hospitalization status because testing is shifting to private labs.
Edit: Let's put it this way: I'll take fuzzy data over no data. Two sets of fuzzy data that match is not awful. You can also use South Korea data, but, honestly, South Korea data is absolutely not going to apply to the USA because their monitoring methods violate so many laws here. For instance, patient identities are public and their cellphones are tracking location of the patients.