For my argument I just replaced "existing" with "not having gold and ponies" and drew parallel not between "specific rooms being occupied" and our civ existing at specific time but between "specific rooms not being emptied of gold and ponies" and "our civ having decent tech at specific time".
It works. Use your own substitutions.
Phisolophical reasonings often latch onto inexplicit meaning of words. If you replace them with different words that fullfill same role in language but have different meaning argument becomes much less apparently profound or even false.
That is why replacing the words with ponies and gold won't work unless you are a pony or sentient gold.