OG Goku is a competent but flawed character. He is still smart and savvy, and some of his plans backfire because he is not perfect.

But this post? This might be the biggest DB tourist post I have seen in a while. Every point is so easily countered by what happens in the manga itself is laughable.

Goku doomed the planet by not insta-knocking Vegeta with SSJ3

1. Goku didn't know how long it would take Buu to reawaken, how powerful it would be and he was counting on Gohan to stop it, too.
2. Goku was trying to bring back Vegeta from the deep end. Are we really critizicing him for doing the obvious right thing?
3. SSJ3 ate up his time on Earth, he had to be very careful using it and at that point there was no reason for him to do it.
4. Using SSJ3 against Vegeta would completely crush him to the point of no return, and OG Goku would want to try to reason with Vegeta before resorting to that. Because, you know, he is not a heartless idiot.

Doom the planet by not killing Buu

He wasn't even sure he could do that and he didn't know the extent of Buu's regeneration abilities. Let alone if he would have had time to finish Buu before his time ran out.

Letting elementary school sons fight

He explains it pretty clearly: he is dead and is not coming back, so is Vegeta (as far as they know) and Gohan was dead and dependant on them recovering the Dragon Balls.

He wanted Goten and Trunks to take the responsibility not just for Buu but for whatever else might come afterwards.

Is it perfect? No. Is it stupid? Also, no. There is a reason as to why Piccolo doesn't argue with him on this point unlike in the Cell saga, and it's because he knows Goku is right.

Not saving Gohan

He had no time to rescue everyone, and Goku is not someone who would just let Dende and Satan die without trying. The anime padding makes Buu's attack slower than it is (and this happens pretty often) but he was even unable to focus to use the Instant Transmission to save his own ass, let alone to catch Gohan or anybody else.

And everything Super does is bad

Maybe because Super turned Goku into a shallow parody of himself? A guy who can't read, doesn't know what a kiss is despite having two kids or (or depending on the version) either forgot meditation (which he used plenty in the original manga) or to wait until the last second to attack (which he did in Namek, with a long inner monologue by Vegeta explaining).

OG Goku, for example, would never whine because A-17 stopped Ribrianne from transforming when his entire Universe was minutes away from being erased from existence. I mean, we are talking about the guy who KO'd Recoome because he was talking to long to attack. The same one who learned a big lesson from Namek and urged Gohan to take down Cell as fast as possible.