Kynes death is a difficult one to handle I agree in film.

I think in a sense they wanted to get it overwith in one scene.

The Spice blow that he dies above is the moment that Kynes concludes “the spice is the worm / the worm is the spice” one and the same.

This is heard while paul takes the water of life in the Lynch version and I wonder if it was at this moment we were to see that spice explosion as he sees and feels his last dying moments. Obviously the baby worms or sand trout is where the water of life comes from also.

Delirious desert collapse and then final death coupled with an explosion from underneath is a weird death scene I must admit.