So your son thinks it is the seal that preserves the food? Oh, to be young and clueless again, huh?

It is, of course, low temperature that prevents or retards the growth of bacteria that results in the spoiling of certain foods. Some foods do not need refrigeration – those that are very dry, that are high in salt, high in acid, high in sugar, etc. – all qualities that inhibit the growth of bacteria. Pizza does not qualify on any of those criteria.

Foods in which bacteria readily grow, however, need to be refrigerated to retain their quality and be safe for some period of time. The US Department of Agriculture only allows perishable foods to linger between the temperatures of 40°F (5°C) and 140 °F (60°C) for two hours. Beyond that, the agency wants you to throw it out. (If the air temperature is 90°F (32°C) or above, it gives you only one hour.)

Now, what is the temperature of your heatless oven? Certainly it is above 40°F – if it has really cooled down, it is essentially the same as your room temperature. The seal doesn't matter; only the ambient temperature matters.

(You don't want to put naked pizza in the refrigerator, either, though. Unprotected, it will absorb odors and flavors from other, stronger foods, and it will dry out in the breezy cold of the refrigerator, too. Wrap it, or put it in the new pizza apartment, which we just discovered, and get back to it within a couple of days.)

And on a related subject, we don't think an oven gasket, which is generally silicon covered fiberglass, and meant to withstand high heat, is remotely similar to a refrigerator gasket, which is generally a vinyl-encased magnet, and is meant to withstand very cold temperatures. It's time for your son to pay a little more attention.