I thought the sheet has only cider vinegar and white vinegar--no balsamic vinegar.
I do like the oil and vinegar well mixed which drizzling separately onto a salad doesn't accomplish. I like raw grated garlic in my dressing and I think that does need to be refrigerated.
I think I could use your idea and mix the garlic with the vinegar. Then I could mix some of the mixture with oil just before adding to the salad. Then I wouldn't have to grate the garlic for each salad.