What Bon is worried about is essentially this:
If everyone can be respawned, does this that not decrease the value of life? Then what happens if Fushi starts treating people the same way he does the grass he steps on? Oh it broke, too bad, guess I'll have to make a new one. Bon wants Fushi to not turn out like that. Additionally, what about the people being revived? Notice that the three are now fairly unhinged. That's also what Bon meant when he 'chose' them. They can't be what they were anymore because now killing themselves just because they don't want to walk to some place? That would happen to everyone if Fushi revived everyone. Same with laws and such. They're all based on the idea that you have the one life and that you want to value it by doing good things. If it doesn't matter even if you die, suddenly no one is going to care about anything except maybe base desires and then you have a global population of suicidal sociopaths. Potentially battle junkies who fight to the death. That's what Bon wants to avoid. He's playing the 'bad' guy so that that doesn't happen. Try to look a little deeper than 'oh he's not doing what the main character wants, definitely bad guy.'
Inevitably yes it also benefits him but if that was all he cared about he wouldn't have stayed at the trial you know. He didn't actually think he would be saved then.