I've seen this line of reasoning with TSLAQ. Tread carefully. Nevertheless, under-reporting cases is exactly the reason to be bullish about the virus.China forces sick people into quarantine hotels, one of them just collapsed. If you have a cough and fever in China are you really going to volunteer to be tested?
Deaths are always more accurately reported than cases. If you die, people is going to know why you did. If you don't display any symptoms or if your symptoms look no worse than a common cold, chances are you will never join the rank of the infected. It's like bad Yelp reviews and Tesla service complaints. Under-reporting of case = vastly higher denominator = lower actual mortality rate