Answer
See explanation.
Work Step by Step
The cosmological principle (page 1504) says that the universe looks the same in every direction, no matter where we are located. There is no “special” point in the universe.
If $H_o$ varied spatially, then from some locations, the universe would be expanding at a different rate than at other locations. You could be in a special place where the universe looks different on a large scale, and that violates the cosmological principle.
However, this does not mean that $H_o$ cannot vary over time. As long as $H_o$ had the same value everywhere in the universe, this would not violate the cosmological principle.