On the contrary, I accept that jhanas are so full of the potential for vipassana, that repeated and persistent practice of jhana (within the N8P) leads inexorably to Enlightenment. I can't imagine any other reason for the SN's Ganges repetition series being applied to the Jhanas, or any reading other than the plain reading of the Pasadika Sutta.
You've not demonstrated the contemporaneity of vipassana with the Sutta Jhanas, and declaring otherwise is not going to change the fact. I'm glad you've acknowledged your mistake in reading the Dhammasangani's "nanasampayutta" as meaning "concomittance" - at least we're rid of that possibility for vipassana in Sutta jhanas on the Dhammasangani approach.
If you're happy using the Abhidhamma with your practice, well and good. But I would suggest that your preference hardly qualifies as a yardstick by which how "Theravada" or a "Theravadin" should be defined.