What would those advocating older people not being protected suggest as an alternative, or is this a generalised non-specific call to martyrdom?
How would it work, if not? Euthanasia? Instead of vaccine hubs, have centres where on your Xth birthday you go to die? Which birthday would people like to see instead of the X? Or if not direct euthanasia, are you advocating an indirect version, where people are not treated for Covid, or Covid-related conditions? Aside from the fact that this would just spread infection, what about the fact that it is older people who have paid to fund the NHS all their lives, which by definition have been longer than the lives of younger ones? Is there a moral case for saying that their contributions are disregarded now that they are more likely to need care?
Do you think that older people should be kept under house arrest, whilst younger ones go about their business? If so, what about people who still work, volunteer or help with childcare? Should they be exempt from being grounded, or be forced to give up their way of life?
In a similar vein, what about the fact that many younger people are saving, and in other ways working towards the time in their lives when they can enjoy the 'fruits of their labours'? Remove that incentive by suggesting that older people's lives (or lifestyles) matter less, and you would also disrupt the lives and mental health of young people. It is important for many people that they have something to look forward to, or to work towards.
With reference to the OP - in this rather strange pact with the government, are you suggesting that the deal also be offered to those with no grandchildren, with the expectation that they would sacrifice their lives to allow yours to have a more 'normal' life for a couple of years? I can't say that I would be happy with that - the sacrifices I would make for my own loved ones are one thing, but I wouldn't expect others to do the same (for mine) any more than I would do it for theirs - particularly when they are total strangers. I also think that had I been offered this deal when I was young, I would have hated to vote for my grandparents to be sacrificed to protect my way of life and future financial wellbeing.
I suppose I don't see any of this in terms of one 'group' sacrificing more in order that others are protected. Societies are interdependent, and there are very many 'useful' members who are in later life, just as there are younger ones who make no obvious contribution, as well as those who are a negative force.