I think the population should be much higher...
So a habble is 2 miles by 2 miles.
That's about 3.2km by 3.2km.
That brings us to 10.24 kmē
Let's assume that 1/3rd is actual living space. (that's a complete fabrication on my part based on nothing.)
That would bring us to ca. 3.41kmē of living space.
3.41kmē = 3410000mē
Let's assume 9mē or rather 10mē (for easy math) of space per person. Close, but not too close quarters. (a little lower that what is deemed minimum appropriate living space by social services in Germany.)
341000 habitants per habble
a habble would then have a population density of 341000 / 10,24 = 33300 people/kmē
Which would be higher than Paris with around 21000 ppl/kmē but less than paris' highest density districy which has about 42000 ppl/kmē
We probably need to cut the number of inhabitants down a bit to account for the fact that you probably can't have more that 2 or maybe three story buildings in the habbles.
So let's just cut the number of inhabitants in half.
That would bring us to roughly 170000 people per habble and about 17000 ppl/kmē
which would then lead to a theoretical maximum population of
...
250 habbles * 170000 people
42.500.000 people per spire.
Sound's like a Borg-Cube to me.