I think you've misinterpreted the paper, while the bike conventional wisdom being wrong is interesting, the story about the membranes seems to be that there was an unknown additional difference in the membrane structure between the thinner and thicker membranes that caused the unexpected result. This doesn't mean that the thicker membranes were better due to being thicker, but because they happened to have a better structure. If the thinner membranes can be manufactured with that structure, they will most likely still be better.

Article abstract says exactly this: "They found that variability in local density most affects the performance of the membranes. Better synthesis methods could thus improve performance without affecting selectivity."