Canonically I think that just made him lose his memory which basically reset the violence conditioning he received as an infant. But I like the severe brain damage interpretation more. For me it is not so much that he became a good boy when he got derpy. Let me see if I can explain.
His violence/kill everything conditioning was based on Sayan cultural ideals such as honor, duty, pride, classism, inherent superiority, etc. While a more "complex" mind might get caught up in these ideas, post damage Goku could see them for what they really are - baseless prejudice and pointless grandstanding. His "simple" mind could see the truth that more "complex" and clouded minds like Vegita never could.
It means that one of the most celebrated, iconic, and powerful fictional characters ever is what we would call disabled (Which sounds ridiculous when applied to a character like Goku.) This brain damage was shown to be a major influence on his life (as major brain damage always is) but did not show Goku as a slave to this damage as is so common, but gave him full agency and in no way dwelt on him as a victim of circumstance. And it also shows this ostensibly handicapped individual becoming the most heroic and powerful person in the universe instead of the usual victim to be pitied.
I know it was a hand wave retcon and I am reading a ton into this that really isn't there, but if you do subscribe to the brain damage interpretation the result is actually incredibly positive interpretation of a disabled character.
P.S. I hope I used to preferred terms right, I tried to look it up but I found somewhat conflicting information on the subject.
