Yeah this is a reason for QT, not only does it keep disease issues out of the tank but it allows your new fish a chance to begin eating in a quiet, peaceful, confined space.
It did take my Powder Brown several days to really begin eating so two days might now be a crisis, but in a 270 you dont have a ton of options except to keep trying and hope for the best.
You might try soaking food in garlic or seachem, sometimes helps entice fish to eat.
Good luck.