His allegience is to Hastinapur and Hastinapur alone.
And In many ways, Vidura is our Conscience. It tells us what is right and what is wrong. It warns us, albeit silently, that there could be repurcrussions of something we that we do or plan to do.
But if we, with our ego and pride ignore it or counter it, it will slink away.
And we will get into trouble for ignoring the Vidura inside all of us.
in other words, Vidura is so powerful, that You need an actual God to stop Him.