ACE2-Fc fusion protein expressed in N. benthamiana as a therapeutic drug against the new coronavirus (SARS-CoV-2)

A group from UC Davis had proposed the idea of using ACE2-Fc fusion protein as a therapeutic agent for COVID-19 as follows,

A group from Chulalongkorn University, Bangkok, Thailand etc. has  developed ACE2-Fc fusion proteins expressed in N. benthamiana leaf, and demonstrated the inhibitory effect of SARS-CoV-2 in vitro. Vero cells were infected with SARS-CoV-2, and then ACE2-Fc fusion protein was applied, 0.84 μg/ml (IC50) was obtained as the inhibitory effect. Why did authors use plants? The advantages of using plants are low cost, scalability of production, and no risks from pathogens of animal or human origin.