The Genoa side was 2-0 up on the night and 4-0 on aggregate anyway.
Sampdoria are to be awarded a 3-0 win and a 5-0 aggregate triumph after Salernitana fans threw fireworks and seats onto the field of play.
The Genoa side had looked set to play in Serie C for the first time in their history when they finished the regular season in the direct relegation places in 18th.
But they got a lifeline when Brescia were docked four points for administrative wrongdoing and dropped into the relegation zone, bumping the former Italian champions and 1992 European Cup finalists Sampdoria up into the playout places.
The return leg of the playout was postponed by two days because several Salernitana players suffered food poisoning after the first leg in Genoa.
ANSA