What does this equation mean?

To make this concrete rather than asymptotic, take the mass of Sagittarius A* as measured by the Event Horizon Telescope, M$\approx$4$\times$10^6\,$M_\odot$ , giving a Schwarzschild radius $r_s$$\approx$1.18$\times$10^{10}\,$\mathrm m$ and a horizon-scale acceleration factor GM/$r_s^2$$\approx$3.80$\times$10^{6}\,$\mathrm{m\,s^{-2}}$ [ 14 ] . At a clearance of just one kilometer above the horizon — a distance smaller than a millionth of the horizon’s own radius — f$\approx$8.46$\times$10^{-8} and the required proper acceleration is already a$\approx$1.3$\times$10^{10}\,$\mathrm{m\,s^{-2}}$ , more than a billion Earth gravities. Even at a clearance of 1.8$\times$10^6\,$\mathrm{km}$ — about fifteen percent of the horizon’s own radius, a distance that sounds generous — the acceleration is still about 10^6\,g . No structure holds together under a sustained load anywhere near that scale; this is not an engineering inconvenience to be solved by better materials, it is the support-energy term diverging exactly where the naive argument wanted its subsidy.