Assisted Dying: the 'Doctors should cause no harm' Argument

Assisted dying allows a patient to end their own life (with doctor-prescribed medication) in order to end their suffering. 
      Some doctors don't want to participate in this, which is fine. One explanation is that 'doctors should cause no harm' and that causing death is harmful. 
      However, this is an argument of emotion, not logic. As these doctors used this argument to try and persuade MPs to vote against the bill legalising assisted dying, having an argument without the rigours of facts and logic is problematic.
      There are three points of contention: not dying as harmful; inaction as harmful; and dying as harmful.

Not Dying as Harmful

If doctors are worried about assisted dying because it causes harm, they also need to consider how not allowing assisted dying causes harm.
      Assisted dying is quick and painless. Whereas the alternative, letting someone suffer by not allowing assisted dying, is long and painful. 
      Sure, assisted dying might be harmful. But it's impossible to refute that preventing assisted dying is more harmful. Not only does the pain last longer but the intensity of said pain is also higher! 
      So, if a doctor's so concerned about not causing harm, then they should allow assisted dying because it's less harmful than the alternative. Thus 'not causing harm' is not a logical reason to be anti-assisted dying.

Inaction as Harmful

Choosing inaction can be harmful. Anti-assisted dying doctors don't seem to recognise this.
      In many situations, failing to stop/prevent harm is considered bad and harmful. Police not stoping a crime, teachers not stopping bullying, no-one stopping abuse of power... why would doctors not stopping harm be any different from these people not doing so?
      Indeed, many medical scenarios already show doctors aren't different in this regard. For example, if someone has been seriously wounded, they're given pain killers. If they have cancer, or infected tonsils/ball bladder, it is removed. But if a doctor chooses inaction, this harms the patient because the doctor has chosen to not do the thing that will end the suffering. 
      Actively letting someone suffer, choosing to not end the pain, is also a doctor doing harm. So inaction can be harmful, including the inaction to proceed with assisted dying.

Dying as Harmful

Some would claim that, as the doctor doesn't cause the patient's death, them doing assisted dying isn't harmful.
      After all, it's the patient who ends their own life during assisted dying, not the doctor. All they do is assist the process by prescribing the necessary medication.
      But the doctor directly assisted that death, directly made that death possible. Whereas patients suffering because of their health conditions would be suffering whether or not that doctor even existed. 
      Clearly, even if death is the lesser of two evils, guaranteeing a patient's death is still harmful. Ending all the bad things in the patient's life still ends all the good things, too.
      But if someone wants to die? That means they've had little to no joy for a while. It means they're going to die from the disease, rather than get better, which means they'll never get the joy back. Ending someone's life when they've got a minimal lifespan left anyway and it will be full of horrors, not happiness, how can we say assisted dying is more harmful than life?

Conclusion

Death is harmful. But letting a patient and their loved ones suffer awfully is far more harmful than death itself. Thus saying 'doctors should cause no harm' logically can't be used to argue against assisted dying.