I'd have thought that more airflow would help to reduce transmission, given that like other coronaviruses it's transmitted by droplets and not aerosol. Droplets would have trouble staying suspended with more air movement, and would be unlikely to make it through centralised air conditioning systems without becoming deposited on some surface within them.
The eating together at communal tables, and any other close-quarters communal activities, seem far more relevant to increased R than the air conditioning system and the free airflow.
Not really, not in a prison: Droplets exist in a continuum, and while most are large enough to drop out of the air, as they get smaller they stay in the air longer, and require less air current to stay aloft. [0]
As such, while the small particles may not exists in sufficient quantities when it is just one infected, or a few infected inmates, but with each infected inmate the concentrations of those small particles will increase. Let's say they're normally 0.5% of the total particle exhalations: 10 inmates get sick through direct contact, and their combined exhalations bring the quantity of smaller, longer lived particles up to an equivalent of 5%. More get sick through contact, bringing it to 20%. At some point, you hit a critical mass where there is a sufficient concentration to infect people, and creates a downward spiral from there.
The eating together at communal tables, and any other close-quarters communal activities, seem far more relevant to increased R than the air conditioning system and the free airflow.