I think that's all reasonable.I did a quick lookup on those phosphates and didn't see anything about them being a preservative. Maybe they have some kind of action that preserves the peptide but that's beyond me. I don't know much about Pregnyl as I've never used it. I'm guessing they formulated it in a way that it stays good longer, they consider the degradation at 60 days acceptable, or they did tests themselves and found that the HCG did not degrade as fast as the Jano test. Since I use Chinese HCG I go by the Jano test.
Another possibility that occurs to me is that there might be some minor chemical alternation to the HCG protein that occurs after reconstitution which makes it chemically "not HCG" according to Jano's test, but which isn't consequential pharmacologically. That could explain the disparity... The only way to resolve that would be a bioassay, which Jano doesn't offer.
In any case that's pure speculation and I see absolutely no reason to give them the benefit of the doubt in the meantime