After 6 months the question ban allows 1 redemption question and I asked this question: Can gas be made to block radiation better? Even thought it did not get down votes it still got closed as being unclear. Did the question ban not lift because it did not get up voted then or was it that it got closed? Now that it has 2 up votes does that mean it is now well-received and can the question ban be lifted early?
Unfortunately, no one outside of the organization (not even moderators) knows what the exact criteria are for receiving a question ban. There are a number of factors that are likely (voting, question closure, deletions, etc.), but it's anyone's guess. The ban can only be lifted by the system.
The question you linked to was not the last one you asked. There is one from November that was deleted by the system. As noted above, I don't know what triggered this recent ban, but these are likely all factors.