This is a basic Athna ashri problem. A child Imam. How can a child be an Imam and the protector of every Shia property, when he can’t be incharge of his own property, according to Quran.
Imam Jawad terminated the line of Imamat that Shia tried so hard to preserve. He was a child and he was black. Because his mother was a Nubian and because the color of his skin was dark, he was called 'Aswad' (The Black one).So even his uncles, the brothers of Imam raza, refused to accept him as an Imam. They said that a syed can’t be black.
And only proof of his Imamat are ahadith narrated by Ibrahim bin Hisham.Can we base Imamat on testimony of only one person, who was a rafdhi?
Al-Kafi volume 8
عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ حَنَانِ بْنِ سَدِيرٍ وَ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ مُحَمَّدِ بْنِ إِسْمَاعِيلَ عَنْ حَنَانِ بْنِ سَدِيرٍ عَنْ أَبِيهِ قَالَ سَأَلْتُ أَبَا جَعْفَرٍ ( عليه السلام ) عَنْهُمَا فَقَالَ يَا أَبَا الْفَضْلِ مَا تَسْأَلُنِي عَنْهُمَا فَوَ اللَّهِ مَا مَاتَ مِنَّا مَيِّتٌ قَطُّ إِلَّا سَاخِطاً عَلَيْهِمَا وَ مَا مِنَّا الْيَوْمَ إِلَّا سَاخِطاً عَلَيْهِمَا يُوصِي بِذَلِكَ الْكَبِيرُ مِنَّا الصَّغِيرَ إِنَّهُمَا ظَلَمَانَا حَقَّنَا وَ مَنَعَانَا فَيْئَنَا وَ كَانَا أَوَّلَ مَنْ رَكِبَ أَعْنَاقَنَا وَ بَثَقَا عَلَيْنَا بَثْقاً فِي الْإِسْلَامِ لَا يُسْكَرُ أَبَداً حَتَّى يَقُومَ قَائِمُنَا أَوْ يَتَكَلَّمَ مُتَكَلِّمُنَا ثُمَّ قَالَ أَمَا وَ اللَّهِ لَوْ قَدْ قَامَ قَائِمُنَا أَوْ تَكَلَّمَ مُتَكَلِّمُنَا لَأَبْدَى مِنْ أُمُورِهِمَا مَا كَانَ يُكْتَمُ وَ لَكَتَمَ مِنْ أُمُورِهِمَا مَا كَانَ يُظْهَرُ وَ اللَّهِ مَا أُسِّسَتْ مِنْ بَلِيَّةٍ وَ لَا قَضِيَّةٍ تَجْرِي عَلَيْنَا أَهْلَ الْبَيْتِ إِلَّا هُمَا أَسَّسَا أَوَّلَهَا فَعَلَيْهِمَا لَعْنَةُ اللَّهِ وَ الْمَلَائِكَةِ وَ النَّاسِ أَجْمَعِينَ
Translation :
Sudayr says I Asked Imam Abu Jafar ( عليه السلام ) about Abu Bakr and Umar. Imam said Do not ask about them. I swear By Allah No one from among us died unless they were angry at both of them. And there is no one from among us today but they are at angry at both of them.The old from among us informs the young about that.They oppressed us and prevented us from having from our right,they were the first to ride on our necks. They opened a door of oppression against us in islam, that will never be closed until our Qa’em rises, or our speaker speaks. He will uncover matters about them, that have been hidden, and he shall hide matters concerning them that have been shown. I swear by Allah, no misfortune or trouble has been caused against us Ahlu Al-Bayt except that they are the first causers of it. Thus may the curse of Allah, his angles, and all of mankind be upon them both.