You have no idea what Gohan is capable of. Even Goku said that Gohan has a power inside him that makes him stronger than anyone else but they never show it, only glimpses. Did You see what he did to Majin Buu? One hit after Goku and everyone else got their ass kicked. He killed cell even though Goku couldn't. Also to don't forget that Goten went SS when he was about 5 and it took Goku over I think 20 years to do that. Super sayains are not to be messed with and especially those who carry Gokus blood.