I am thinking of gravitation in terms of an emergent field analogy. It is not the same as your suggestion, but you are motivationally not too far off from what started my inquiry
Also look at this business of NLED (non linear electrodyamics) and GR
https://arxiv.org/abs/1512.07579
also see work done by Camara
https://arxiv.org/abs/astro-ph/0402311
they consider if the cosmological constant is time independent or time dependent, and go to the regime of a quantum bounce at the start of nucleation of a new universe
The aether in terms of gravitation may be, as you described it, partly described by
https://arxiv.org/abs/astro-ph/0402311
My work is roughly congruent to when one has a time independent cosmological constant, as they describe it
You may wish to consider if your gravitational aether model is congruent with their work.
Thanks for your view point and outlook.
As to the matter of "cold" and an anti gravitational push, all I can say is that various models of the cosmological constant. Dependent upon the initial sign of the cosmological constant, it conceivably could be connected initially as an "anti gravitational" push as you referred to it. That if the sign of the cosmological constant were negative.
As I diagrammed it out, using enhanced quantization, the cosmological constant initially has a positive sign.
If the sign were, instead negative, then the idea you have of an anti gravitational push could be entertained.
That is a matter of further research and speculation though.
Thanks for your contribution to this discussion