Two reasons:
The most obvious reason is it would expose the lie about them being semites, much less 'God's chosen people'. They claim to be descendents from the patriarchs Abraham, Isaac and Jacob, yet it's the MOTHER'S DNA which determines their 'Jewishness'.
The deeper reason is to hide the fact that they are indeed a separate race of hybrids. What we know to be 'Ashkenazi' DNA markers are in reality markers of much more ancient bloodlines which go back all the way to Fallen Angels and Nephilim. They are literally a non-human species.
Mike
