The A-site spinel material CoAl2O4 is a physical realization of the frustrated diamond-lattice antiferromagnet,a model in which unique incommensurate or “spin-spiral-liquid” ground states are predicted. Our previoussingle-crystal neutron scattering study instead classified it as a “kinetically inhibited” antiferromagnet, where thelong-ranged correlations of a collinearN´eel ground state are blocked by the freezing of domain-wall motion belowa first-order phase transition at T∗ = 6.5 K. This paper provides new data sets from a number of experiments,which support and expand this work in several important ways. We show that the phenomenology leading tothe kinetically inhibited order is unaffected by sample measured and instrument resolution, while new lowtemperaturemeasurements reveal spin correlations are unchanging between T = 2 K and 250 mK, consistentwith a frozen state. Polarized diffuse neutron measurements show several interesting magnetic features, whichcan be entirely explained by the existence of short-ranged N´eel order. Finally, and crucially, this paper presentssome neutron scattering studies of single crystalline MnAl2O4, which acts as an unfrustrated analog to CoAl2O4and shows all the hallmarks of a classical antiferromagnet with a continuous phase transition to N´eel orderat TN = 39 K. Direct comparison between the two compounds indicates that CoAl2O4 is unique, not in thenature of high-temperature diffuse correlations, but rather in the nature of the frozen state below T∗. The higherlevel of cation inversion in the MnAl2O4 sample indicates that this behavior is primarily an effect of greaternext-nearest-neighbor exchange.