There are many people who will die from many common diseases that are communicable, including the standard flu. This argument doesn't hold up under scrutiny.
At risk people (the vast, vast minority) need to self quarantine instead of having the unrealistic expectation that the everyone should instead of them.
Things that can kill a 70 year old include such threats as falling over, or moderate exercise. At no point in thousands of years of human history have we seriously tried to keep all the 70 year olds who were alive at the start of the year alive at the start oft he next year. It isn't possible.
60s is a different thing, but at 70 there are very real questions about whether a quarantine is even worth it. Do you risk losing half your remaining lifespan in a quarantine, attempting to avoid a 30% chance of death? The calculus is grim, but that doesn't mean it should be ignored.
At risk people (the vast, vast minority) need to self quarantine instead of having the unrealistic expectation that the everyone should instead of them.