>> As the size of the black hole goes up, its overall density must decrease.

> The center of a black hole is infinitely dense. That's why it even exists. The event horizon is not the black hole.

>> and the fixed density of our observed universe

> Our universe is expanding. It's density is not fixed.

These are both correct and germane points. So why was this post downvoted? Physics isn't a popularity contest, it relies on evidence.