Hey, I work over at a garage in bath, only do cars but we do punctures everyday-they would have drilled it from the inside out to plug it properly (if you do it from outside in and and nail has gone in at an angle, your not gonna plug the hole and it's still gonna leak) and they use a rubber plug which will wear the same as a normal tyre so it should be ok, the hole that's left looks like where the head Of the nail has been pushed into the tyre but not gone all the way through?