In what sense can it be scrutinised? To what end can the court scritinise the act? Overturning the act itself?
Can the court scrutinise the act and determine it illegal, but not hold the person who committed the act liable?
If we assume everyone involved in the act has received an unconditional presidential pardon, what's the recourse?
We do it all the time.
Suppose that an agency writes a regulation. Someone sues and a court finds that said regulation is not supported by any regulation, that the regulation is illegal.
We don't throw he person who wrote the regulation in jail.
Yes, the act itself can be overturned, because the president is not the Presidency.
Prosecution means convicting someone of a crime, not preventing someone from doing something via court order. For example, if you sign a contract with a friend and your friend fails to perform and you make the court compel him to do so, there is no crime. If he doesn't follow the order, the court will hold him in contempt. Contempt is not a criminal matter. Judges can hold whomever they want in contempt.
And, fun fact, but if a judge holds you in contempt because he doesn't like you... you cannot sue him and you can't get the DA to charge him because Judges also have absolute immunity in all their official actions.