I don't believe there is any requirements for modders, but it is commonly accepted that unless you state that you can't support something, that you will be supporting it. It seems like people are expecting it more, which isn't right, but to be honest if you can't support it then you need to put something at the top of your resource stating so. I have all the respect in the world for mod authors/designers and think it is unfair, unjust, and unkind when someone calls them out for not being able to support one of their resources, especially when those resources are free, but it is something that people have come to expect, support that is, from all authors. It is just the way things are; people want support and updates and they could hardly care about your reasons for not updating/supporting your product.