That's been reported before.
Frick if I know. Perhaps it is limiting liability for violation of FDA or other food and health/safety regulations enforced by the Department of Agriculture or Department of Commerce. Even those regulations would largely require proper administrative rule finding and the like,.
In all seriousness, the other alternative explanation is this is the equivalent of trump waving a stick he claims is a magic wand and proclaiming himself King of the Moon. He has been known issues such Fantasyland unenforceable orders multiple times in the past, being egged on by a combination of ever present sycophants and unitary executive theorists In The West Wing.
Food production facilities are pretty damn essential, and it seems to be the Federal government would be justified taking emergency measures to shield them from liability under a "Crisis Standard of Care" type framework.
And so many are also illegal immigrants, and we know how easy Trump has been things for them.
They might literally become too sick to work, enough at one plant that most get sick, and then infect many many more.
https://www.virginiamercury.com/2020/04/27/meatpacking-plants-have-become-coronavirus-hotspots-across-the-u-s-in-virginia-no-ones-giving-workers-much-information/?fbclid=IwAR2D9N_EEXBw7SG1xWHOOUvuiQLwONHQoZRguzoCb40rMrg88l_d-AC7T3s
