All of the tasks are pointless. The boulder rolls down, the hotel for sure can accommodate him, the ship will be reborn. Which is most pointless seems to be the paradox now. "Is he happy?" implies that pointless tasks please him.
Is he happy refers to the end of Camus' book The Myth of Sisyphus where he concludes "One must imagine Sisyphus happy." The oft omitted penultimate line gives the meaning Camus was going for. "The struggle itself towards the heights is enough to fill a man's heart. One must imagine Sisyphus happy." So one does not have to make believe Sisyphus to be happy but one must consider him so.
Each time he approaches the switch, the boulder rolls down back again, at least till this day. You can't really know, it's entirely up to Sisyphus. Each time you're anxiously awaiting him, each time you don't know how to decide, each time nothing happens.
The real question isn't if sisyphus is happy, he's working out each day the whole day, why wouldn't he. The question is, are you.
The person at the train track switch is not observing Sisyphus or the switch. Sisyphus is then in a quantum superposition between rolling the boulder into the hotel or the ship.
Actually, the hotel manager could relocate guests from each Nth room to the (2×N)th (every even-numbered room), as there are infinity rooms. This way, there'll be as infinity free odd-numbered rooms as there are infinity booked guests. Sisyphus can then choose any odd room for himself and another for his boulder.