Gohan one-shots. Mismatch.
End of DB Goku would whoop Demon's arse! Goku against Raditz could do almost nothing. Gohan released his fury and did some damage to a 1400-1600 can't remember. And we saw on the scouter that Gohan rose quite high well over a 1000. Goku was about 400-600.
It just makes (some) sense for Gohan to easily beat the Demon.