Why wasn't Kaio revived by Shenlong when he revived everyone that were killed by Cell?

[Natasha Romanoff]

I mean, Kaio was directly killed by Cell. Why wasn't he revived?

 

[Dagon]

Plot hole.

 

[Papasmurf]

Goku said he refused to be revived.

http://comic.dragonballcn.com/list/0.Dragon_Ball-buyao_daolian_ya/0.jp_Kanzenban/DRAGONBALLvol28/174-j4Uen.jpg

 

[Hector]

Because he was above Shenlong in hierarchy.