In my experience, that sediment that comes out of the first glass isn't all the sediment in the keg. Just like racking from the fermenter, there's a sort of hole where some sediment was sucked out near the tube and the rest of the bottom of the keg still has sediment in it. As long as you don't move the keg, you don't get any more sediment. If you do ever have to move the keg, your beer may cloud back up until the sediment resettles (which always takes less time than the initial settling for some reason). It's still fine to bright tank in the keg. I do it more often than not. But if that's a dealbreaker for you, I'd rather you be aware of it up front. You could always do the aforementioned jump to a fresh keg after settling.