Originally posted by leonidasGalactus was severely weak and the planet had no energy it was a dead world. That's why he didn't absorb it.
g failed to absorb apok in that x-over, and he blasted but didn't ko darkseid. g also failed to absorb the world of the dire wraiths for much the same reasons.
Darkseid's beams had no effect on him. Galactus at his best dominates apokolips I mean DD did.