Spin 2 theory and connection to GR

[kdv]

http://arxiv.org/abs/1105.3735

I have a question about the paper that haushofer mentioned. In the paper, the author states that

Moving on to helicity 2, the required gauge symmetry is linearized general coordinate invariance. Asking for consistent self interactions leads essentially uniquely to GR and full general coordinate invariance .

I am not sure what this means. If we quantize GR, I know of course that we end up with a massless spin 2 graviton. Here, we treat the metric as a quantum field so it is clear that general covariance leads to a gauge symmetry in the quantum theory we obtain.

But let's say with start with quantizing a spin 2 classical field in a flat spacetime. We may have a gauge symmetry which a priori has nothing to do with spacetime coordinate transformation and general covariance. Is the author saying that consistency of a massless spin 2 theory automatically leads to a condition on the spacetime it evolves through? Even if initially the spin 2 particle has nothing to do with a metric? Or am I completely missing the point?
Thanks in advance.

 

[PAllen]

That is what the author is saying. This result has derived (with varying degrees of rigor) long ago, including by Feynman. Besides spin two, there is the feature that graviton interacts with everything, including other gravitons. It is this together with spin 2, that leads almost uniquely to a theory indistinguishable from GR.