The Ottomans and others who built nearly identical hinged bows didn't bother with any sort of lock or keeper.
IF (and that's a huge if) the string should break or a limb snap, the hinged bits should NOT hurt you, even if you have sensitive hands(!). IF/WHEN something gives, you'll be holding the bow in the center which should keep the pieces together for the few milliseconds it takes your brain to realize that something broke and tell your hand to "drop the weapon".
If you're overly worried, make a thin leather 'sleeve' handle which can be slid on/off the center, or wear a manly-man bowhand glove/armguard combo like I do when shooting off the hand.