Amana Eamich from the USDA FSIS tells me the FSIS did not shut down any part of Agriprocessors yesterday. Even so, multiple people from Postville claim the beef line did shut down at 12:15 yesterday.
Assuming the Postville natives are correct, this means…
…either Agriprocessors shut down the beef line for its own reasons or the rabbis shut it down.
I'll post more details if and when they become available.