So here's why that tire is not repairable: The belt ends are there.
The belt ends are the most highly stressed area (volume) in the tire. Remember the Ford/Firestone thing a few years back? Belt end failures!!
Risk?
It was estimated that the Firestone tires were failing at a rate of 1/2 to 1/4 percent. I've estimated based on a survey done by the RMA (Rubber Manufacturers Association), that the failure rate for repaired tires is about 3 times higher than the failure rate for unrepaired tires.
If I take into account that in the 14 years since the Ford/Firestone situation, there has been a 10 fold improvement in failure rate, then we are talking about a repaired tire failure rate of 0.15% - or about 1 in 700.