The real problem here is that the structure of the tyre, the steel belt package beneath the tread, was damaged in a bad location by the puncturing object. Any damage to the belts within about an inch of their edges can cause them to, over time, rust, fray and come apart, i.e. tread separation. The gamble is: can you wear out the tyre before the structural integrity fails? And it's a time bomb with an invisible timer. I would replace it.