I think "sacred cows" refers to the past presidents (referenced through extra capitalizations) that will be exposed as the Trump Train enters Benghazi and 9/11 territory.
…and then the North Korea expose.
I think the [0] delta between the POTUS tweets means that you read them together as one message.
The extra capitalizations refer to G "W" Bush, G "H" W Bush, Bill "C" Clinton, and Hussein "O" Obama.
These past presidents are the referenced "sacred cows" thought to be untouchable, but they will be exposed for "Collusion" and "Obstruction" in due course as MI and POTUS execute their well-crafted plan.