@Chelly, I. think your directive makes a lot of sense. I pretty much feel the same way, although I might allow my daughter (RN). to make a call about a temporary use of a ventilator. Fortunately, many doctors are not rushing to ventilators as quickly as before. So hopefully, if you ever get CV (and you might not), you can survive it without those invasive measures.
I think having those instructions forces doctors to try other things. Antivirals need to be used early on. So do not wait to go to the ER if you have a sudden loss of sense of smell or taste, or a new cough or, especially, shortness of breath. Lots can be done without a ventilator.
If my family wants me on a ventilator while they come to terms with what's going on, I'm okay with that (I will be in no shape to know or care at that point). I was on one in January, a bit unexpectedly and only briefly - as I had feared, even a minor surgery necessitated a ventilator for me, an asthmatic. I think it was out of abundance of caution, but boy did I like the anesthesiologist and her explanation of why she did it - I was of course under sedation.
My biggest worry is that if I die, our very good health plan dies with me and my DH is uninsured. He would have to spend a big chunk of money on health insurance, plus the cash-out of my main retirement account is not as great as if I were to live another 10 years. It's good to think about these things though.