As far as the OP goes: this MD isn't arguing for fixed state termination at 75, so far as I can tell. That said, he is certainly advocating such a position, which is sometimes taken up as 'retailing infamy' on the forum in the view of one poster or another.
He is arguing for a form of self-euthanasia - I assume with the mitigation of pain symptoms. The choice to publish an article - especially in The Atlantic, which has a pretty large readership - is clearly not taken up solely as an egotistical device, particularly so in this case since he elaborates and supports his case extensively. While some might call the issue partially aesthetic - and what a great word - he means what he says, and he thinks you should agree with him. If he didn't aim to convince you also, he could have stuck the article on his blog, or into any other reasonably easily accessible orifice capable of storing it.
It's a curious thing: big laws are built of elements, and among those elements is public acceptability and traction. For example, smokers are exiled further and further away from buildings in some part because non-smokers don't like smoke: smoking kills, sure, but there's also an aesthetic component to it. If he aims to convince others to stop their clocks - or at least stop running - at some life-changing state, then is he not also arguing that you should take up with his views? How long from there to a social acceptance sufficiently wide to result in legislation forcing compliance with the new meme? I realise this sounds like a slippery slope, but social advocacy requires an appreciation of the issues and potential consequences.
Is he right or wrong? Or do his conclusions flow - excuse me - from the tacit support of a socioeconomic system in which cutting off parts of the body is taken as a healthy step for its survival? How far we have come in our assumptions, no?