Doctor here who makes and discusses DNACPR decisions regularly.
It doesn't sound as if the discussion has been done well. If the doctor did say that he was a burden (in those words) then you should absolutely complain as that is inappropriate language and likely to be very distressing to hear.
However, I suspect that the discussion about how he has carers coming in was intended to demonstrate that your dad has at least moderate frailty. Frailty is independent of age - I have met 80 year olds walking 10 000 steps a day and 65 year olds that can't walk more than a few steps and need help with washing and dressing - the second would be frail, the first not.
There is excellent evidence that the more frail a patient is, and the more health conditions that they have, the less likely they are to get a successful outcome from CPR.
CPR also works best in someone who is generally well and suffers a sudden event such as a heart attack that causes a cardiac arrest, and is quickly reversible. In older, sicker people cardiac arrest is the end of a long process of decline (often an admission to hospital with a relatively minor condition, but on the background of continued physical decline), and far less likely to be reversed.
It's not like on the TV where they press on the chest a few times then give a shock and the patient is back. It's a brutal process, and like any brutal process e.g. chemotherapy, we should only be putting people through it if there is a benefit.
At 80, needing carers multiple times a day, and with significant health conditions, including heart failure, the chances of surviving a cardiac arrest are incredibly low. It's notable that the success rate from cardiac arrests because of heart rhythms that respond to electric shocks such as the ICD/ CRT-D will give is somewhat better, but in fact most cardiac arrests are not this type and electric shocks do not work (and a defibrillator would not go off during one of these episodes as they are designed to go off for certain heart rhythms which are fast rhythms, not for the most common cardiac arrest heart rhythms such as asytole and PEA (pulseless electrical activity)).
Even if the heart restarts after CPR, almost every patient after a cardiac arrest has to go to ITU (intensive care) and be put on a ventilator - something which is incredibly brutal on the body and the mind, and has quite significant risks of its own. A large number of working age adults who have an unplanned ITU stay are still not working 1 year later - that shows the physical toll on the body, and a period of time where the brain and body has been deprived of oxygen also takes its toll. In the circumstances you describe, your dad would not be a candidate for ITU, and this means that the breathing tube in his throat would be taken out and he would be made comfortable on the ward.
Having good mental capabilities, a good quality of life, or being a fighter does not determine the success of CPR - the underlying cause and the patient's frailty and health conditions do.
Patients can refuse any treatment they want, but cannot demand any treatment they want, and doctors are not required to provide a treatment that they don't think will work. This is not just an opinion - it is the law. Ultimately the decision whether or not to offer CPR is a medical one, and sometimes the waters get muddied as people are asked what they would want, when in fact what we should be saying is "This is my medical decision, do you understand/agree?(see below for what happens if patients/relatives don't agree)"
Doctors are required by law to discuss DNACPR decisions with patients (if they have capacity to understand) and relatives - the only exception to this would be in an emergency where there was not time to do so. This allows the patient or family to ask for a second opinion if they disagree with the doctor's decision. If this happens to me (which is rare) I explain that while we are awaiting the second opinion, that the patient remains for CPR. If the second opinion disagrees with me, then the patient remains for CPR. If the second opinion agrees with me, then the DNACPR form is signed and it is binding.
It sounds like perhaps the conversation with you was done poorly, but it's quite likely that if I were the consultant seeing your dad with the history you've given then I would be recommending DNACPR as well.
In terms of the defibrillator, I think that the Emergency Department (A&E) doctors have got a bit muddled - you can certainly have a DNACPR without switching off the defibrillator, although when it is clear that a patient is dying there are ways to "switch it off", but this is done at the very end of life.