You have confused and trivialized that somewhat.
Gribkowsky is in prison for corruption and tax evaision, not receiving the bribe from Bernie. And while the payments have been confirmed as a bribe, the argument is that it was in response to Gribkowsky blackmailing Bernie about his tax issues, and not related to undervaluing F1 to aid a sale, which is what Bernie is accused off.
Its not as simple as just whether it was a bribe (it was), its about what the bribe was for and who it may or may not have affected.
I assume that if Gribkowsky is found guilty of blackmail then there's the possibility that Bernie would not only get let off, but could also get his money back? That would go down well on here, that's for sure.
Personally, if F1 loses Bernie then the sport is history. The crazy old man is one of the only things stopping the FIA destroying the sport, or the teams ripping it apart themselves.