Prithvi wasn't WRONG in running after Sanyo, but this was the WRONG TIME to do it....
When there is a problem with the Kingdom, the King should ALWAYS BE PRESENT!!!
Basically, running after Sanyo wasn't the right thing to do, given that time period....especially considering the fact that there was some 'garbar' going on in Delhi....
It's kinda like what Someshwar once told him: "Ek raaja ko sabse pehle apne rajya aur praja ke baare main sochna chahiye".....