That is over-simplistic - until you have had PCA treatment related ED for 9 years, you cannot imagine the emotional impact of having your meds taken away. I have been there and am still living it. John does't have mechanical ED but the psychological damage means that without a little magic tablet, nothing is going to rise.
That's not to say that taking 10mg every 3 or 4 days won't keep the levels up enough for Gilo to carry on as before, but it is less likely.