I agree 100% with Rob and with Angel. No one knows your body better than you do and no one knows what your body can and cannot do better than you. This disease is different for everyone and that 79 year old guy may not be suffering from the same symptoms of this disease that you suffer from. So, as Rob mentioned, if the therapist is not a Rheumatologist who knows about this disease, then he should keep his opinions/remarks/ignorance to himself!
I hope that we are able to help you as you try to understand this disease and how it affects you. You are doing the right thing by learning as much as you can and we want to help you to do that!