The bar will outlast the kite every time so unless you are too tight to buy a new bar with your new kite, don't ever worry about it, rinsing it has no benefits.
Never ever rinsed a kite or a bar in the last 9 years and my gear is lasting exactly the same as anyone else.
The only time I had issue is when my garage got flooded by rain and the bar actually got into some fresh water and mould appeared.
Got fixed by going back to its usual diet of salt water only