Stewards question

[MaTH716]

For anyone who didn't see Aqueduct yesterday, the first 7 races were conducted in a fog that gradually got worse as the day went on, before cancelling the last 2 races cause of dangerous conditions. The fog got so bad, that track announcer John Imbriale pretty much called a few of the races from the Trackus chicklets on the screen.
It dawned me after the conclusion of the 7th when a longshot went gate to wire, what would happen if there was a foul and an objection after the race? There's no possible way any of the stewards would be able to see any sort of foul. If the stewards cant see the entire race and have the ability to police it, for the protection of the jockeys and bettors, how dont they take it upon themselves to cancel the card earlier?