/* the more stable the Bose-Einstein condensate of hydrogen isotopes */
I wouldn't call the condensate or Rydberg matter the stuffs which occur during fusion, no matter how cold it is. It's more exact to call it degenerate matter
https://en.wikipedia.org/wiki/Degenerate_matter
It's true, the atoms are heavily entangled mutually inside such a matter in similar way, like the atoms within boson condensates, but this artifact is very unstable and it decays fast.
The difference is just in temperature dependence: the degenerate matter likes it hot, whereas the boson condensates or Rydberg matter are sensitive to heat instead...
/* The fundamental engineering challenge is to remove heat from a reaction zone fast enough to keep the temperature down */
This is just what the Astroblaster model solves: the thin rods of dense matter formed during linear collisions of atom nuclei serves as both effective absorber energy, both its radiator into an outside.
Despite the conventional wisdom, the absorbtion of neutrons or gamma rays with matter is quite stochastic and rare process: there is lotta place at the bottom, as Feynman once said.
It means that the neutron or gamma ray photon must pass many atoms before it will finally hit something, because atom nuclei are tiny with respect to distance between atoms.
The nuclear collisions during cold fusion are different: the long chains of entangled atoms get arranged along straight line and the photons or neutron get absorbed along these lines too.
Their absorption is therefore very effective and it's finished after short path. In addition, such a rod-like artifacts have large surface area and they're cooling fast with thermal collisions with another atoms, before they decay.
It makes big difference in comparison to pin-point collisions inside hot plasmas, where the energy of collision must release and spread from a single point. It leads into radiation of many particles with high energy, which is the main source of energy loss during hot fusion (not to say about their radiation effects).