Nah, if Jon takes Sansa's way then he creates discord among the Northmen. The lower houses would be wasting time vying for his favor instead to training and gathering food and fortifying for the coming war. Lets say he places a family like the Cassels or the Pooles then THEIR ancestral enemies turn on Jon..or even new enemies pop up because they didn't get raised up.
By keeping the Umbers and Karstarks in place he earned GENERATIONS long loyalty. Alys Karstark and Ned Umber woulda been killed and their heads fed to Ghost if it was any other short sighted leader. But in stead he raises up two kids who KNOW they really should be dead and makes live long bannerment out of the....and he keeps the North looking like the North.
we're saying the same thing tho. i agree with you, jon's decision was the right call when it comes to the umbers and karstarks. but that doesnt mean sansa wasnt right too. jon needs to keep in mind that the right answer isnt always the smart answer. and no one on his current team is better equipped to help him in that area, while also genuinely keeping his best interests at heart, than sansa. even if he decides to disagree with her 90% of the time, he needs to be open-minded about what she has to say. she is far more experienced when it comes to how the current power-brokers rose to prominence, and all the behind-the-scenes fukkery that can turn a noble leader into a dead leader.
jon, to date, has been too much like ned in that area; he thinks the right answer is the only answer. that's why he got killed!