Ok, @shyamd pointed out this publication https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3344236/figure/f4-ijms-13-04632/ which seems to suggest the experimental bulk modulus (~40 GPA for a glass) might be closer to the MP value that the value from the tensor you pasted above, which gives a VRH bulk modulus of ~ 100 GPa, though this is probably not sufficient to say one way or the other for sure.