Here is one significant problem with this preprint:
"The health system never had a requirement for asymptomatic employee test screening. Most of the positive tests, therefore, would have been tests done to evaluate suspicious symptoms."
In other words, there could have been people who caught Covid-19, but because they had already had it, the symptoms were mild and they didn't get tested. It may be possible for these people to still be infectious (we don't really know this). For a proper study, they need to look at a decent population of people who have regular asymptomatic screening.
"The health system never had a requirement for asymptomatic employee test screening. Most of the positive tests, therefore, would have been tests done to evaluate suspicious symptoms."
In other words, there could have been people who caught Covid-19, but because they had already had it, the symptoms were mild and they didn't get tested. It may be possible for these people to still be infectious (we don't really know this). For a proper study, they need to look at a decent population of people who have regular asymptomatic screening.