Avon's 'road hazard warranty' is very generous, but you'd be suprised how quickly you get through that first millimeter of tread.

In this case, British Starndards are recommendations, not legal requirements. I'd be more inclined to follow the manufacturers' guidelines.

Anyway, in our ever litigious society, if a tyre failed following a repair, the repairer would probably get sued. This is why fewer and fewer places will repair motorcycle tyres.