There's no part that talks about primatial jurisdiction, because the very idea of the Presiding Bishop as a primate is a new one, only loosely incorporated in the Constitution. The constitution does give General convention full power to institute a number of alternative pastoral schemes, including bishops for foreign lands, missionary bishops, the creation of new (even non-geographical) dioceses, etc. General convention, or the Executive Council acting when GC is in recess, could certainly participate in any such pastoral scheme it wanted to. There's no clause here that clearly rules out participation in the Primates' scheme, such that the House of Bishops could point to it and say, "This clause precludes our participation."
But how many of the Bishops, do YOU think, took time to look over the Constitution before voting for their statement, hmmmmmmm?
What must the argument have been? - that somehow the Pastoral Council would be able to direct 815? Surely not, for even a cursory reading of the Primates' proposal disproves that. The Council would have nothing to do with anything in TEC except as regards the Primatial Vicar, and except to represent the Primates in negotiating the necessary particulars of this temporary arrangement. What about this felt threatening to the Bishops? Their statement seems, upon reflection, to be based on ignorance of their own canons, fear of primatial intevention, fear of the 'plundering' of the church, and, dare I say, wounded pride. Ignorance, fear, pride, love of money - high motives, all.