It would be fine for them to argue that it's implausible, just as it would almost make sense to say "I don't see how smallpox could be cured. So I intend to rot

It would be fine for them to argue that it's implausible, just as it would almost make sense to say "I don't see how smallpox could be cured. So I intend to rot to death." But the argument I was responding to was, basically, "I accept that it could be possible to cure smallpox, but the idea of not dying that way is repulsive to me."