being actually innocent of the crime isn't the courts job according to him.
It's generally not. The job of the court is to provide a fair trial, the job of the jury is to make the decision of guilt or innocence, and perfection at all costs is not a reasonable goal either. But please keep reading.
The discovery of new evidence clearly shows that a trial was not fair. It may have been fair at the time, but part of human progress is uncovering new truths, and our justice system should reflect that. DNA evidence has been an example of that -- people were convicted before it was testable, and exonerated afterward. But sometimes investigations are incomplete as well, and new evidence is honestly discovered, such as the Robert Durst handwriting and confession obtained during The Jinx.
On the other hand, allowing new evidence to result in a new trial incentivizes the willful withholding of evidence. Keep some evidence in your back pocket, and if you lose a trial, simply present it as new evidence and voila, retrial!
We need to come up with rules for new evidence to limit abuse, but the goal should still be to provide a fair trial, weighted toward keeping innocent people out of prison, but not at all costs.