Perhaps the Fox legal team looked at the Judges order and determined that a bit of self-protection by Fox News was called for.
Or maybe Fox News has gotten wind of what Arpaio and Perry are going to spring on the public in early February, since The Donald is a regular on Fox, as is Arpaio.
You just have to assume that Arpaio has had off screen conversations with Fox News regarding his impending posse revelations...including agreement not to discuss it on the air until the timing is right.
Interesting. The plot thickens. Things are going to get ugly.