waterfall

I'm asking because some of you state that flat spacetime can't model black holes... meaning even between the planck scale and event horizon, but yet atyy said spin-2 field in flat spacetime is equivalent to General Relativity for spacetime that is covered by harmonic coordinates which atyy thought can include the event horizon up to the planck scale. So this means spin-2 field in flat spacetime can model black holes.

So can flat spacetime model black holes or not? And if you add spin-2, why can it do that?
Why, is there flat spacetime without spin-2 field? Are these distinct concepts?