I agree. I think there are other factors that the authors specifically did not study like human susceptibility. We basically don’t know the pathways and virus load needed to contract the disease.
Route is through any mucous membrane, including the eyes and inhaled droplets of contaminated fluids, through any open wound, through sexual contact, consumption of contaminated food.
The virus survives and has been detected in the semen of a recovered patient 61 days after he was pronounced "recovered". It was capable of infecting someone through sexual contact.
What we do not know is if there are circumstances through which the virus can infect through transdermal contact.
Fomites are a known vector, including removing contaminated PPE improperly.
The virus can survive on surfaces for hours, longer if out of direct sunlight and at cooler temperatures, indefinitely in the dark at -70C. (I haven't been anywhere that was that cold, but close at -60F).
The list of what we don't know will get shorter.
Infections were attributed to most likely vectors in the past, and with the increase in cases and awareness, the less likely or apparent vectors will become more evident.