Just because you don't see how it can be that fast doesn't mean you should immediately jump to false advertising. Think of it like cooking chicken to a safe temperature, you can do it sous vide at a lower temperature and still get safe chicken it'll just take 8 hours or you can throw it in an incinerator at a thousand degrees and have it sterilized in a few seconds.

Sterilized is more than just the amount of time it's also the amount of exposure, an extremely strong UV light needs significantly less time than a weaker one