Yeah I guess only the label can answer that and it could be anything from moving it away from Christmas to other album releases at the label. We could probably guess a hundred different reasons and they could all be wrong. I don't know if Testament have a long term contact with NB, they don't appear to have their own label and using NB as distribution like EMP seem too, but you would reckon if the band were unhappy they'd also be making more of a stink about it.
Of course it could just be that NB read the other threads on this forum where currently it seems to be very incrowd to hate on Exodus, Testament, Annihilator and F&J. If they read some of that waffle in those threads I think we're lucky to get a new Testament album at all