i actually liked this one. Thaks @seigezunt for giving the time frame. I am surprised no one commented after the finale to see how they felt it connected. (I saw the finale first, so the "previously" got me confused).
So we see that Pike didn't know about this incident, so clearly before he came on board. (But funny he didn't read about it)
I personally like to think all the "red tape" stuff happened off-screen, so that Tilly didn't secretly beam off the Queen, but rather she specifically requested that Tilly do it. (Being the Queen and all, the incident was wrapped up neatly).
This also shows in a quirky way how Tilly can be a great Captain. She is building the trust of WORLD LEADERS , and can leverage those relationships at later dates (like she did here).
How long can Po's species last? If she is tied to the planet (which i would NOT take a completely literal), could she appear in the future season 3? If so, perhaps she and Saru's home planet could be interesting bridges form the past to the future.
ANyway, this episode felt very "Star Trekky" in theme. It reminded me of Diane Duane's 2 part DC comic story in that feel of it.
Po became the queen of a very important planet, so they probably redacted the entire incident, if anyone but Tilly even knew about it.