Coronavirus phylogeny and evolution
FYI coronaviruses have proof reading activity, unlike HIV, its a huge genome, unlike HIV. Thus the point mutation rate is unlikely to be as rapid as HIV.

The phylogenies in this paper are not really about the evolution or epidemiology of the virus. The trees used for viral taxonomy and form part of the International Committee for the Taxonomy of Viruses (ICTV) assessment in officially naming the virus. The ICTV is the authority in naming a virus. The ICTV essentially called it SARS2 as opposed to the WHO who used the name COVID-19. Thats the point of this paper and will be massively cited. 

The broader evolutionary epidemiology of "SARS2" is for further studies. The Lancet paper on 22nd February gave some indication of this (and I suspect you know about that paper).