Or the 3rd decision I think you overlooked is award the goal and go back to the cautionable offence.Law 14: "Once the referee has signalled for a penalty kick to be taken," the ball is now in play.
Law 5: "the referee" "allows play to continue when an offence occurs and the non-offending team will benefit from the advantage,..."
Note the law 5 application supercedes any other situation when referee is required to stop play (unless specifically stated). So there is no requirement for law to say, play advantage here or there in specific situations. It's already covered in law 5 quote, which also includes penalty kicks.
So ball is play, an offence has been committed and the non-offending team benefits from continuing. Play advantaged and allow the goal. For me this is both the common sense answer and the by the book answer.
The only variation would be if the keeper is already on a yellow. What is now beneficial, retake and one less opponent or goal against 11 opponents? A lot of factors involved for this decision, the score at the time, minute of the game etc. However I think you can't go wrong with allowing the goal. It's the least risky decision and everyone would/should be happy with it.
On the AR signal, I would wait the extra second even if I see it. I would still want him to signal. It would make selling my decision easier whichever I go.
Death to match control but an entirely possible conclusion to this scenario.