There is also the option that he paid a year worth of rent in advance, which emptied his bank account, and now he has no liquidity, but has a place to stay for

There is also the option that he paid a year worth of rent in advance, which emptied his bank account, and now he has no liquidity, but has a place to stay for the next 12 months. But you are right that this is not clarified anywhere in the post, and the math as described does not add up.