I find this whole 'bhanga: jhana or not jhana' discussion to be faulty, since it is too general.
It's not like you are analyzing someone's description of a certain meditation experience and then commenting on what you think that was, you are talking in broad terms.
'Bhanga' can mean different things to different people. 'Jhana' can mean different things to different people (Sutta Jhana vs. Visudhimagga Jhana).
If you take the 'Vipassana Jhana' approach (Mahasi Sayadaw), then the experience of Bhanga is within the 2nd Vipassana Jhana.
But from my own experience, what Goenka calls 'Bhanga' can be experienced in different ways. You could have a 'Bhanga-like' experience in the First Nyana (Mind & Body) where you feel the whole body as vibrations, but you can also have a 'Bhanga' experience (which is probably what Goenka means) at the 4th nyana (Arising and passing away), which feels much more intense than Nyana 1. It could be felt as the whole body exploding into vibrations, lack of orientation of body and so on.
It is simply a matter of one's own personal experience, and talking so broadly is really point-less, I think