If Pier Giorgio Frassati's body was found incorrupt when his tomb was opened, wouldn't that be considered his second miracle?

A second miracle must be attributed to the intercession of Blessed Pier Giorgio Frassati in order for his cause of canonization to proceed. However, the mere fact that his body was found to be incorrupt is not sufficient. In rare cases, incorruptibility may be considered miraculous. Generally, however, incorruptibility is only considered to be evidence of the holiness of the person. Why then is the tomb opened during the canonization process? This is normal procedure for authenticating and preserving the mortal remains of the holy person.