Currency wasn't a terrible store of value. The essay says as much:

> Ok, so why not sell the grain and store something less perishable, like money? Sure, you can’t put it in a bank, but you can just keep it. And indeed, our ancients do this

The problems with currency are listed as:

1. Someone can come into your house and take it.

2. Ordinary farmers cannot afford enough currency to replace the value of a failed harvest. (An entire year's revenue.)

3. In the event of a famine, the price of food rises, making currency a poor hedge against famine.

Only #3 applies to how valuable currency is in a famine, and it remains superior to local social ties when the famine strikes.

But because of its unaffordability and undesirable correlation with famine, it is not the favored solution to famine. It's just a much better solution than local friendships.

You read the wrong essay; the standard defense against famine is discussed in the following one:

> So we’ve established what the big landlord gets out of working with the smaller subsistence farmers around them – they get labor to put more of their large holdings under cultivation and even a degree of labor flexibility with wage laborers and sharecroppers drawn from the existing rural population. In this sense – and I want to stress this – the large estates need the rural small farmers to survive. This is why, even in periods of rapid growth among large landholding estates (like the steady expansion of latifundia in the Roman late Republic and early Empire), there remained lots of these smaller farmers. But what do the small farmers get?

> Just like the smallholders could establish horizontal ties with fellow small farmers, they could also try to establish those ties with the big fellow in the big house. Of course the mechanisms for establishing the ties were different: few peasants could banquet an aristocrat and most aristocrats would be insulted by a suggestion of an alliance through marriage. Instead the ties were strictly vertical – that is they were unequal. They often began with the farmer working at least a bit as a tenant on the big farm, but also typically included political support, sometimes military support (that is, coming out to fight when the large landholder did, often as common troops in his retinue) and no small amount of social deference.

> In exchange, in theory, the large landholder could provide the ultimate backstop against catastrophe – even a catastrophe that might ruin an entire village or rural area all at once.

In the event of a famine, the farmer has two options:

1. Leave the stricken area, in which case he's dependent on his stock of currency.

2. Hope for relief to be delivered by his social superiors, which depends on their stock of currency.