That’s weird I’ve never heard of having to boil it yourself?
They come pasteurised more often than not, just to kill off the bacteria so it can be stored in jars at the supermarket for longer, unlike yoghurt.
Whenever sauerkraut is heated, it’s killing the beneficial bacteria which is one of the best probiotics known to man. It defeats the main purpose for eating it.
Obviously it will still bring great benefits such as A and D vitamins released by the fermentation process, but you really want the bacteria alive so they can kill candida in the gut and still produce the good by-products for your body.