I know a little bit more about orbital mechanics, and I know that the internal structure of a planet matters for the stability of an orbit. While at larger distances the effect becomes small enough to ignore, it never really goes away. Whereas a black hole is indeed thought to behave like a point mass.
The Dirac Spinor equation is extremely standard, and GR would be the more famous one. The only "leap of faith" here is having the metric to be the functional of the matter wave, and not just the stress-energy tensor (which is the mainstream semi-classical approach).
Simply sharing here to prove authorship + sharing something interesting to HN.
edit: Though I note that I should have quoted Birkhoff's theorem instead, thanks for the pointer.
Yep, 100% it only applies to black holes (after enough time, so they can radiate the weird parts, but this time is short in human scale)