The B's problems are real, because it's a really, really challenging aircraft - in some ways (not all) the most challenging of the three. But the int I get from the team (and I have good contacts) is that there are no major stoppers right now - it was interesting to note that the recent 'quick look' report did not bring up any major B peculiar issues. Lost of common ones, though.
Not doubting your contacts but saying that there are no potential big issues
with the F35B that could still lead to its demise is a somewhat simplistic representation of the trueth I think.
Not too long ago that the GAO and other sources involved in the program where , and at present still are, severely concerned about the weight and CoG issues with the F35B model, limits are razorthin and it is no longer deemed useable on the shorter carriers (think the new Oz Navy ones eg) with a useful load of weaponry.
Besides all the other issues it has in common with the other models it still has a fair amount of big problems specific to the B model which until today remain unsolved, not the least with regards to its very complicated propulsion setup (eg, 2 attempts to solve the blistering panels at the exhaust failed to solve the problem
AFAIK).
the inlet airflow door that still needs a redesign, granted not really a showstopper, too high fuel consumption, noise issues, etc.