The aim in this is not to exhibit his correctness of...
The aim in this is not to exhibit his correctness of thinking and judgement or deep sagacity but to show that there was unity and concord between him and the Caliphs so that attention should not be paid to the fact that in some matters they also differed and that mutual clashes had also occurred. History shows that Amir al-mu'minin did have differences of principles with the Caliphs and did not approve every step of theirs.
In the sermon of ash-Shiqshiqiyyah he has expressed in loud words his difference of opinion and anger about each regime. Nevertheless, this difference does not mean that correct guidance should be withheld in collective Islamic problems. Again, Amir al-mu'minin's character was so high that no one could imagine that he would ever evade giving counsel which concerned the common weal, or would give such counsel which would damage public interests.
That is why, despite differences of principle, he was consulted. This throws light on the greatness of his character and the correctness of his thinking and judgement. Similarly, it is a prominent trait of the Holy Prophet's character that despite rejecting his claim to prophethood the unbelievers acknowledged him the best trustee and could never doubt his trustworthiness.
Rather, even during clashes of mutual opposition they entrusted to him their property without fear and never suspected that their property would be misappropriated. Similarly, Amir al-mu'minin was held to occupy so high a position of trust and confidence that friend and foe both trusted in the correctness of his counsel.
So, just as the Prophet's conduct shows his height of trustworthiness, and just as it cannot be inferred from it that there was mutual accord between him and the unbelievers, because trust has its own place while the clash of Islam and unbelief has another, in the same way, despite having differences with the Caliphs, Amir al-mu'minin was regarded as the protector of national and community interests and as the guardian of Islam's wellbeing and prosperity.
Thus when national interests were involved he was consulted and he tendered his unbiased advice raising himself above personal ends and keeping in view the Prophet's tradition to the effect that "He who is consulted is a trustee" never allowed any dishonesty or duplicity to interfere.