No, requiring the existing master password won't help. A drive by miscreant with access to an unlocked computer with an unlocked DB can delete all the DB entries. If the DB is locked they can just delete the DB file. KeePassXC can't defend against this, that takes properly functioning versioned backups.

It's the Internet Corrolary to Murphy's Law: your embarrassing posts will be available online forever, but any useful information you want to find later will have been deleted when you next look for it.