general relativity - The largest black hole

The Schwarzschild radius involves an expression in terms of Newton's constant $G$, the mass $M$ inside a radius $r$, and the speed of light squared $c^2$. Current estimates of the universe's matter density are about six protons per cubic meter. But, the $M$ inside a sphere goes up as $r^3$, while the "time curvature" coefficient is $1 - \frac{2GM}{c^2\, r}$. So this coefficient is bound to hit zero for $r$ large enough. The $M$ outruns the denominator as a function of $r$.

I calculated that this coefficient hits zero when $r$ equals 13.54 billion light years. Question: Is this any evidence for our universe being one very large black hole?