The angular momentum distribution of the compound nucleus is a fundamental characteristic of the reaction dynamics and can provide insight into reactions involving neutron- or proton-rich projectiles. Specifically, following the fusion of ⁶He with ²⁰⁹Bi (at center-of-mass energies of 18 to 27 MeV), 212At is formed by the evaporation of three neutrons from the compound nucleus. The decay process leaves the residual 212At in either the ground state (Jpi = 1-, T1/2=314 ms) or a metastable state (Jpi = 9-, T1/2 = 119 ms). The ratio of the number of residual 212mAt to the total number of 212At residual nuclei is sensitive to the original momentum distribution of the compound nucleus. The measured isomer ratio is consistent with that predicted by standard models. This agreement is observed even at the lower energies where the measured three neutron evaporation cross section is greatly enhanced compared to model calculations. While the inclusion of coupling to the neutron-transfer channels improves the agreement with the observed cross-section data somewhat, the predicted isomer ratio then diverges from the measured ratio.