Not really, the fault might have been fixed way before then (such as 0850, 0830, or even 0805), and the powers-at-be might have decided to open at a time that was on the hour.
Agreed. The speed that automated trading occurs these days is truly staggering, Getting in on something even a split second before someone else can make a huge difference. Sensible thing to do is a have a concrete point for everyone to get back through the doors. On the hour just seem like a logical synchronisation point.