There is no single way to make wine, you will always find different opinions etc. Rinsing with the so2 solution is just good practice when transferring wine that is complete and has been sulfited. In this case sanitizing isn't the biggest issue, though it doesn't hurt. The rinse residue helps maintain the sulfite concentration in the wine which always drops during a transfer. Other winemakers will not rinse, but will transfer the wine and wait a period of time, a few days to a few weeks, and then test sulfite levels and adjust accordingly. I don't use citric acid in any of the sulfite rinses that contact wine as additional citric usually results in higher VA over time. My rinse solution is about 14 grams per quart.