My speculation: somebody in the GOP had been pushing Trump to take Mitt as SoS. The idea was floated as a rumor, public opinion among Trump supporters duly noted, and the idea was quashed.
Does anybody here think that Kellyanne would really go rogue at this point, or that Trump would not be watching the Sunday shows, notice what she was saying, and let her know within 20 seconds to cut it out?
An inadvertent sentence, maybe. Running through multiple Sunday talk shows before getting the word, no.
This was a well-planned message from the Trump team.