No one is ever write or wrong. There are simply differing opinions, with predictions helping in the long run to settle matters one way or another. This is how scientific theory works.
Re the Denisovans. The only human fossil remains relating to them so far come from the Denisova Cave in the Altai Mountains. Various other fossils (like the Penghu jawbone) have been proposed as possibly belonging to Denisovan, but more work needs to be done to establish their extent geographically.
We do not know why the Denisovans were in the Altai region. All we know is that they were there for at least 50,000-70,000 years, and so it wasn't simply their final outpost. It was their home.
Denisovan DNA has been detected among various of the tribes and clans of central Asia, North Asia, and in Mongolia. See:
Qin, Pengfei, and Mark Stoneking. 2015. “Denisovan Ancestry in East Eurasian and Native American Populations,” Molecular Biology and Evolution 32:10, 2665-2674.
The levels are not high, but why should they be. Those who mated with the Denisovans in southern Siberia prior to 40,000 years ago moved on towards East Asia, leaving little trace of their descendants behind them.
No really work has been done to establish whether Denisovan DNA can be found in ancient human remains. This will be very important to try and understand where exactly their hybrid descendants reached.
Moreover, there is no evidence so far that Denisovans were in either Melanesia or Australia. They may have been, but we simply don't know. What is probably more certain is that Denisovan hybrids reached both these territories, and at a very early date indeed. However, these were primarily modern humans with pronounced Denisovan ancestry.
In new book Denisovan Dawn, co-authored with Greg Little, I discuss the impact of Denisovan hybrids on Australia and Melanesia, and exactly what the presence of Denisovan DNA in modern populations actually means. The upshot is that its all about easterly migrations of modern humans moving from SW Asia through Asia, interbreeding along the way.
Concerning the Cygnus-Giza Correlation. Much much has been done on this in recent years. Rodney Hale and I wrote an academic paper on the subject, which can be read about here:
The material is included also in The Cygnus Key.
The upshot is that the Cygnus-Giza Correlation is real, and works in both the horizontal and vertical place, and thus is three dimensional in nature.