Note that it says "...for the preceding Qualification Year." I assume that the clause would be invoked if someone did a huge CC churn at the end of the calendar year to get MQD to meet the next status tier threshold, and then returned/charged back after the start of the new medallion year. I'm only guessing, but I don't think DL would tinker with medallion status tier changes based on mid-year MQD fluctuations from CC spend.