You can always move the room guests into the next room before the boulder reaches them.
Besides, the boulder will have to destroy half of the rooms before it reaches the other half. And half of those first before reaching the later half. And half of those first before reaching the later half. So Sisyphus can only ever bulldoze an inifinitelly small share of the rooms.
Hum… There are certainly way more than dozens. Both of those are on the millions, in a population of billions that means there would be thousands of people with both interests even if they were independent.