You question why he would flirt and then ignore you, but earlier in the post you say that he has poor social skills and conversations are often forced. Seems to me like you have answered your own question. I suspect he either simply didn't know how to sustain flirting via text, or figured that because you had already made it clear that you wanted to have sex with him, that he had done everything he needed to do and was just waiting for you to send him the pictures he wanted and/or propose where and when to have sex. Either way, he hasn't appreciated what he needs to do to turn you on and push this forward to the two of you actually having sex. That may well not be his fault, but equally it's not realistic to simply expect you to make all of the effort and/or have sex with someone who you are not connecting with and, despite you thinking he should be able to, is not turning you on. I understand why it is jarring for him and get why he feels like you played with his feelings, but I don't think you did. You openly tried to engaged with him and were very clear with what you wanted, but the two of you ultimately didn't connect and you didn't want to pursue it. There's nothing wrong with that at all, even though he's bound to be irritated by it.
So I don't think you necessarily overreacted. You could certainly have kept on trying, but equally it's unreasonable to break things off when you did. And whilst I think it's a bit strong to say that he was right to be mad because I don't think you did anything wrong, I certainly understand from his perspective why he is mad. Ultimately though, this is something he needs to get over. He had an opportunity had having a fling with a girl and couldn't follow it through. It's something he needs to learn from.