So? You could have just said "Thank you for your post, but I meant I want them to not have the restrictions at all" instead of being rude to them and yeah it was rude (you're still being rude infact). If someone posts information you already know you can relax instead of getting defensive. Not everyone is going to understand immediately what you mean at all times (nor would they know, without mind reading powers, what info you currently are aware of already) so when people post and you think they might have missed the issue you raised then you calmly clarify your idea instead of trying to put them down.
Telling them they stated the obvious is just a less obvious way of putting down someone's intelligence. If you are going to get so worked up over someone simply posting something that was probably just trying to offer you info/help then maybe you shouldn't bother posting.