Tit for tat doesn't work in relationships. Is it that he made the commitment or is that he has no interest in helping out with your friends? Is it because it wasn't your idea? Did husband volunteer you because he is being an Ass or because he was simply doing what people do in times of illness which is to support each other?
Pick and choose your battles. If its an issue for you to do it then I would tell him since he is home this weekend to purchase some pre-cooked meals and deliver them before he leaves.
If its really not an issue and it just makes you mad that he doesn't offer equal support then I would most likely get over myself and help the folks.
Husbands, even non-A ones, are known to commit their wives to such deeds LOL.