User blog:KillRoy231/Bobby's deal with Crowley - Plot hole

If you remember the end of Season 5, Bobby sold his soul to Crowley for Death's location.

Typically the Hellhounds kill you when your time is up, and you go to hell. But it isn't the Hellhounds that directly send you to hell, they just do the killing necessary for the damnation. If you die in any way after selling your soul, even if it's before your time is up, you go to hell.

So, in the Season 5 finale, Lucifer kills Bobby by snapping his neck. That would send Bobby to hell right then because of his deal with Crowley. When Castiel revives him, that should be the end of it.

But what's this? In Season 6, Crowley still "has" Bobby's soul, as he is refusing to return it, revealing his true colors, and Sam and Dean have to threaten him with burning his human bones to get him to return Bobby's soul and officially release him from their deal (though Crowley still gets Bobby sent to hell anyway after Dick kills him, but then he just got a rogue reaper to do it).

Why didn't Bobby's death and revival in Season 5 release him from his deal with Crowley? When Dean sold his soul in Season 2, and was killed by Hellhounds and sent to hell in Season 3, Castiel reviving him got him off the hook, so why not Bobby? Is it because Bobby's time wasn't up yet, where Dean's was?