This was a favorite episode of this season thus far. However, it was not without its flaws:
It was a bit (very) contrived that EVERYONE on the ship would take time off to see Bortus sing, leaving the entire ship abandoned without even a skeleton crew watching key systems apparently. (Remember, nobody including the Captain could "know" about the procedure, so this had to be a legitimate invitation which also somehow gave all people on active duty the night off to see some random officer sing?!?) The irony is that while they took great pains to show the ship essentially abandoned, they really wouldn't need to do this. Aside from the command crew, there wouldn't be a reason for the ship to be completely stripped of people. I can't imagine random ensign #3 who just happens to walk by knowing about or caring about a random medical procedure taking place in the medical bay.
Plus, the medical procedure still uses the ship's medical facilities, which still pins liability squarely on the Union. When they were discussing this, I honestly expected Issac to take the child down to the planet to complete the procedure (perhaps using portable medical equipment.) Otherwise, the admiral is right, allowing the procedure on the ship only makes the captain look insubordinate AND stupid.
That said, I did like the overall message and dilemma of the story. It also reinforces the unintended message of asking for forgiveness rather than permission.

All I could think of is Kirk, (paraphrasing) "The word is no. I am therefore doing it any way!"