Cosmological Redshift

How do masses cause cosmological redshift:
Suppose I'm sitting in the center of a huge, spherical, thin cloud of matter with the same mass density throughout. There's no gravity there. I'm moving outward at a constant speed. The hollow sphere principle applies. The mass that causes gravity increases with R³. Since gravity depends on 1/R², this increases with R. The gravitational redshift of an object increases with 1/R, so for mass at the center, the shift would increase with R².
However, if mass also exists outside the sphere, gravity cancels out. However, the redshift remains, just as it exists at an inner Langrange point of stars. At infinity, the redshift is therefore infinite, caused by mass.
Assuming the radius of the event horizon is T=G•M/c², for every average density of a uniform mass distribution, there is a radius at which the redshift is similar to that of a black hole.

Ludwig Resch