It's the redshifts of galaxies that are used as a yardstick.
Quasars have always been mysterious. For a long time, people
suggested that their redshifts were due to something other
than cosmological redshift, just because the distance
implied by a cosmological redshift meant they were insanely
bright, small objects - "QUASi-stellAR radio objects."
Finally, the cosmological redshift became a consensus
on the "preponderance of evidence."
So it would seem this finding is stirring a pot that's
been on the back burner for a while.
( This is the view of an interested amateur. )
And all of these building blocks (redshift, doppler,rate of expansion, temperature, limitation on temperature and visible light increase due to expansion, all of these things theories cite the other ones as proof.
What I am saying is that since there are objects that do not conform to one of the most basic theories, then how can any of them be right. It seems there is a lot of circular reasoning going on. Even Einstein's theory of relativity was defect and had to be corrected by the 'cosmological constant', which Einstein later admitted was the biggest mistake of his life.
Why is the cosmological constant still used?
What is the true density of the universe?
The big bang and then either infinite expansion or eventual collapse theory is based on the density of the universe.
So how can we be sure of the density of the universe if we do not know it's size?