The difference between the results using D(0) and p(0) needs to be discussed. From several experiments, it seems likely that positive kaons are formed at lower density of H(0), while negative kaons are formed preferentially at higher density. In the present experiments, that should mean that positive muons should be formed using D(0), since the signal in Figs. 5 and 6 is slightly lower for D(0). This agrees with the conclusion that D(0) here gives more positive muons and thus a time constant close to the free muon decay. The reason for this density effect is however not obvious. One might speculate that in D(0) only every second nuclei is a proton, and thus that the 2 p → 3 K transition is less likely, but this does not give any clue to why positive muons should be formed more often in that case. Another possibility would be that at high density, neutral kaons are formed preferentially and at low density, charged kaons are more common. However, charge asymmetry is required to explain the observations in such a case.
Anybody's guess as to what the ratio of negative to positive muons created in Mizuno's reactor could be. Clearly there are many possible LENR reactions going on here to generate excess heat, muon-catalysed fusion of D-D just being one of the more well established mechanisms among others. I would replicate Mizuno's reactor with thick stainless steel walls because D would be absorbed into the Fe metallic lattice and possibly undergo fusion here too, thin walls may form small (NAE) cracks letting in air etc