If his father and grandfather were mostly busy explaining...
If his father and grandfather were mostly busy explaining the knowledge of Ahlul- Bait (a.s.) and outlining their school of thought and its methodology concerning fiqh, Islamic beliefs, Qur'anic exegesis, politics, morals, etc., which they took from their forefather Imam al-Sajjad (a.s.), who took it from his father Imam al-Hussein (a.s.), who took it from his father Imam Ali bin Abi-Talib (a.s.), who took it from the Apostle of Allah (s.a.w.); Imam al-Kadhim's (a.s.) role was manifest in his political militancy.
He peacefully challenged the rulers, and, as a result, was thrown into prison. He acted wisely according to the conditions of his time. It is only natural that the "official" historians, who adhered to the rulers out of fear of their power, would endear themselves to them, falsifying the truth, lavishing the qualities of greatness, sacredness and idealism on these tyrants. They tried hard to drown the voice of right and avoid the mention of rejection and opposition to the oppressors.