I think you did a very good job with the argument between Harry and Dumbledore. Though I think Harry missed a telling point: If I had stayed put, "sir", or taken time to try to contact someone, Susan would probably now be dead or hidden away somewhere being tortured by DEs. I took the only available course of action to save lives." While responding in anger and attacking Dumbledore's poor decision-making may have worked well, it left Dumbledore's and Snapes estimation that Harry acted irresponsibly intact. But neither has offered a viable alternative. Perhaps sometimes the only good choice is the irresponsible one.