Gortash probably only pays lip service to Bane and is using the Cult of the Absolute for his own benefit. Each of the Chosen are radically different from the other and the hows and whys they worship one of the Dead 3 is probably deeply tied to their own personal motivations and background.
There is something he says that screams like potential foreshadowing...a brittle alliance cannot be mended, it can only shatter. And as we all know the alliance of the dead three has not been anything more than brittle since before they became gods, and I doubt that it is more stable now. Even as they work together now in BG3, it's more than likely they each have schemes to come out on top at the expense of the others. I wonder precisely how aware Gortash is of this. And the decor on his clothing is also very interesting. I wonder if his loyalty might actually belong to the dragons...or if he is a dragon himself.
