what, no
Goku's plan was for Gohan to get angry and thus make his incredible potential show up
Gohan getting angry was 100% a requisite of Gohan's plan
Piccolo pointed out that he hadn't discussed this with Gohan, yes, but that doesn't undo the fact that Goku was counting on Gohan undergoing anger to bring out his hidden potential, thus SSJ2.
You have no proof he wanted Gohan to get angry, why would he plan for that and then take the actions he did during the Cell games. Gohan's outbursts weren't always triggered by rage, just his own life being in danger was enough when he was really young. If Goku wanted to trigger Gohan's rage he would've let Cell beat the living shit out of him, instead he gives Cell a and senzu and sent Gohan out expecting him to unleash his power in the middle of their fight. That's where Piccolo calls him out, Goku thought Gohan loved fighting and that the thrill and life threatening excitement would trigger his hidden potential. If Cell didn't go out of his way to torture everyone Goku's plan would've been a complete failure.
I can get around that easily, because come Buu saga, both Goku and Vegeta have surpassed Gohan
the three years thing is about Super Saiyan Blue; back in the era where SSJ2 was relevant, another round of ROSAT could easily have done the difference for Goku
how is that getting out it? That's 7 years later, we have no idea when Goku or Vegeta obtained SSJ2 and that's also after they realized that SSJ2 actually existed. Goku was on a time limit before the Cell games and once again, HE. SAYS. IT. HIMSELF. You have absolutely no answer to this.
and you still didn't answer why Goku wouldn't just train Gohan more.
Piccolo and Vegeta also knew that Gohan would unleash more power if Gohan got angry; they had experienced it first hand
yet how do you explain Goku not being surprised by the transformation, but Piccolo and Vegeta being surprised
according to you, Gohan had exploded in anger before with no transformation, so all three SHOULD be surprised
because Piccolo and Vegeta(no one actually) had no faith in Gohan's hidden potential to bail them out, Vegeta couldn't believe that Gohan could be stronger than him or Goku. Piccolo was emotional, knew Gohan hates fighting and only saw a scared a little kid. Goku was the only one who had the had the plan of Gohan winning, everyone else thought he was crazy. When Gohan transforms Goku's relieved and happy that Gohan did it, everyone else is shocked that it actually happened and he ended up being so powerful.
as an aside I didn't really like that whole thing too much, felt like it justified Goku for just believing in his son when he WAS wrong about Gohan.
and I will bring it back home here. Goku definitely still had a toooon or room to grow. it was super out of character that he just stopped training during the Cell saga
of course Goku still had room to grow, that's not the arguement, could he had gotten strong enough to beat Cell before the Cell games? According to Goku, no, so he had to believe in Gohan, that's it.
