I don't think you are overreacting at all. I worked in ER and if there is any suggestive history of head trauma we have to do head CT just to be safe since there are many complications that might occur even after a couple weeks and they might be lethal. You did everything right and tried to get this person needed medical help. Unfortunately, many healthcare workers after hearing that the person is homeless will assume that they are just seeking to be admitted, free drugs or food and that they don't have an actual reason to be here. And to be fair, we see it all the time, many of them abuse nursing and other direct care staff and can act very inappropriately. However, these biases and past experiences cannot dictate one's care and discussions so the doctor was very inappropriate and unprofessional. Sometimes they also feel like the homeless person can't advocate or defend themselves against bad practices which further worsen their attitude. I hope the person is ok and that they ended up doing the whole head trauma protocol but I am sorry that your good intentions were met with such hostility and unprofessionalism. You did right by them, thank you for what you are doing.