Your buddy is stuck on textbook fermentation rules. Taste buds vary wildly, and some of us just can't handle that intense puckering sour. Rinsing might wash away some surface probiotics, but the good stuff is already deep inside the cabbage. You're still getting the gut health benefits without the face twisting shock. Why suffer through food you don't enjoy? What's the actual goal, perfect purity or making something you'll actually eat?