Henderson's "Bomb" is one of the lamest moments of the show
In season 5 Christopher Henderson apparently tries to kill Jack using a bomb. Not only does this fail completely, but it doesn't fit Henderson's M.O. at all.
Also, later he goes home without realizing Jack is in his house. The writers made him look like an idiot for two episodes in a row.
He certainly had many valid opportunities to kill Jack, and yet the best they could come up with was a half-baked bomb? A bomb that cannot kill one person who is trapped in the room?
Season 7's twist with the Jonas Hodges assassin was much better. Hodges had a valid reason to keep Jack alive. Otherwise there would be no way Jack could survive that either.