Ethically — assuming such engineering is even possible without unexpected consequences — it sounds like a trolley problem, only instead of 6 on the default track and 1 on the alternate it might be 6 million by default and 1 million with the airborne cowpox analogy. (Numbers completely made up, of course).
Procedure? When not doing the procedure will (to continue using my totally made up hypothetical numbers) cost 5 million more lives? That’s much less clear to me.
(Reality is more likely to be “we reckon it might save 5 million lives net, but then again it might combine with the original to make something both virulent and highly transmissive”, but the joy of hypotheticals is I can ignore that).
SARS-CoV-2, as terrible as it was, wasn't nearly as bad as it could have been: a better-adapted, more transmissible, and more lethal first wave.
And if that scenario were playing out, a human-engineered firebreak, even at the cost of many lives, isn't an obvious ethical wrong. Difficult decisions.
Yet when China does it (accidentally or not) it’s considered unthinkable for our political class. If you think people in Washington couldn’t be less worried about their electorates. If anything COVID has been a boon to hide their massive incompetence diverting discussions around mandates, vaccinations and other woke virtue signaling.
political and ethical suicide