[AnriXuinriZ]

I don't think that there's any point in continuing this discussion with somebody who doesn't know what "falsifiable" means

Your argument amounts to "the theory is robust, therefore it isn't falsifiable." Most theories are robust (otherwise they wouldn't be theories - they'd be hypotheses or conjectures), and even many disproved theories (like Newtonian mechanics) are still "mostly correct," so this is a rubbish argument. Poking holes in (let alone falsifying) an established theory is difficult, and typically the task falls to eminent scientists, not to scientifically illiterate history teachers.