According to PWInsider, the company pitched the idea of doing a pre-tape segment with Grado at the Bound for Glory event for Santino Marella’s debut with the company. It’s being said that Santino actually declined the segment so instead they did a cameo where he just sat at ringside in the first row.
In regards to Santino actually wrestling a match, it seems highly unlikely as he’s retired from professional wrestling due to a neck injury. While not confirmed, it’s possible that he just portrays an on-air character if the company decides to use him in the future.