Giving the Sauerkraut a quick rinse does remove some of the Probiotics and good bacteria but it doesn't remove all the probiotics and good bacteria.
The sauerkraut being rinses will also reduce the sodium content so if you're not able to eat much sodium then rinsing the sauerkraut is a good idea to reduce your sodium intake.
Although I just eat the sauerkraut without rinsing because it keeps most of the nutrients and good bacteria in the sauerkraut.
Rinsing Sauerkraut does also help make the sauerkraut taste better and removes the bad taste that some people don't like of the sauerkraut.