besides the fact that the interplay of all the contributing factors to sea level is complex and they have no idea other than pure guesswork as to prominent cause 11 thousand years ago, even the very fact of determining the world wide sea level 11 thousand years ago is not an established fact, in fact it cant be, any physical measurement 11, 000 years ago can only be based on theoretical assumptions and tremendously lengthy extrapolations
of course if one is bamboozled by the authority of scientism even on the deep theory end of the scientific continuum, you can come to believe anything
even that the gases and metals and rocks and water on the earth (which itself, along with the rest of the universe came into being by the explosion of something smaller than a poppy seed)
these atoms and molecules picked themselves up by their bootstraps and became you.