The whole process is managed by AI filters. Etsy has always maintained that no manual changes will be made once the badge result has been decided. You can try marking the unanswered message as spam now, and within a couple of days the stats should update to reflect this, so that your score is back on track for next month's badge assessment. It MAY work, many have had success, but from what I have read, if the unanswered message was a Help Request, you may not be able to mark it as spam, simply because a Help Request, by definition, ALWAYS requires an answer.
The whole SS program is inherently flawed, simply because most of the metrics are out of the control of the seller, and bear little to no relevance to true customer service. However, with all due respect, your reaction (moving to another venue) is overkill. You still got the badge this month, and in all likelihood will still get it next month from what you say. If you value the badge that much, why would you throw it away, just because you were marked down on one metric, but still made the cut. That's a bit like throwing the baby out with the bathwater.
