The king of impact to FICO score is paying on time. Everything else is a choice how to use credit.
That's not what we're talking about here. We're talking about a specific scoring factor, revolving utilization and how going from a best to worst case scanario with it can constitute a 70-90 point change in scores. Going from best to worst here only involves a reported balance change of around $165 which is of course quite insignificant when someone is using their card naturally. Your suggestion that the OPs score may be only impacted around 10 points based on this is way off base.
When you're talking about a profile that's in bad place with respect to the largest sector of the FICO pie, the last thing you want is the [close] second slice of the FICO pie to be in a bad place as well. I'm quite certain that the OP or anyone for that matter would much rather seeing their scores 70-90 points higher, especially if their scores are already in a less than favorable spot.