2 reasons
Walz is a socialist in simpatico with Harris
Shapiro would ignite riots in Chicago in 2 weeks, killing doornail dead the sugar high.
Prediction:
The Chicago riots are still on. Every group who wants something from the Democrats.
And a Gentile VP pick will be insufficient appeasement for the Jew haters.
Also ordinary criminals will be out in force to take advantage of the chaos.