Yes, the spatial pooler has inhibitory interneurons.
Full diclosure: I only read the abstract. The paper’s primary finding is that basal dendrites form a single compartment, and apical dendrites each form their own compartment. Now I assume that the paper only investigates excitatory neurons, but I would expect that inhibitory neurons are affected by compartmentalization in the same way. The compartments are caused by the shape and electric properties of the dendrite, which should affect both inhibitory and excitatory synapses in the same way.
If you would like a review of inhibitory interneurons, here is where I keep my notes: Inhibitory Interneuron Review and Discussion
I hope this helps!