I can certainly imagine scenarios where failing to get poverty food aid cannot be adequately remedied by any amount of money later.
If you look at many other injunctions for irreparable harm, like a lot of the gun rights cases, they would only apply it to the actual groups that sued like "members of second amendment foundation" as it can be too difficult to generalize to the entire populace. I suspect this might apply for snap; a judge may find some certain families could undergo irreparable harm but not perhaps rule the entire class of people receiving it would yet.