I don't know enough about this to say for sure, but ACE2 receptors are at the molecular scale, and them saying "3D models of oral, airway, and intestinal tissue

I don't know enough about this to say for sure, but ACE2 receptors are at the molecular scale, and them saying "3D models of oral, airway, and intestinal tissues" seems to suggest if this is a computer simulation, then the simulation scale is large. I don't think they can capture molecular dynamics as well as large scale effects at the same time. edit: yeah. if you read the paper, they got some human models (real clumps of cells) from some biotech company and ran tests on it.