Yeah it's purposefully done like that in order to give a sense of plausible deniability
Well no, TTP's trying to create an image of itself and distancing itself from these acts which led to them being ostracized by many people. Claiming the attack does not fit into their Agenda in that regard.It doesn't make sense they would distance themselves from something that could be a big achievement
But anyways, I think one can conclude that this attack certainly had TTP involvement at the senior level if not all of the stakeholders in their group were taken into account then at least some were. Either way, means it was TTP who did it.