I don’t think many aspects of the Great Barrington Declaration are realistic and given where we are with the vaccine now (it wasn’t when they made it), undesirable. The idea that we can put workers who have antibodies into nursing homes and lock them away for two months is an experiment is not palatable to western societies. The additional challenge of intergenerational homes they also have not answered convincing (IMO).
But we are living in prolonged chaos through rolling lockdowns, that is undeniable. You point to 2/3 months of economics without looking at the big picture. The longer term picture in Ireland was a budget deficit greater than our EU colleagues, to pay for lockdowns. And what has come at the end of these restrictions, a third lockdown. And more chaos in our hospitals. The strongest point that the GB people have is that in actual fact, continued lockdowns put the most at risk at greater risk. Rather than having one window of significant exposure where the State throws the kitchen sink at protection, you have multiple windows. The GB crowd actually confront reality, risk and trade offs - unlike those who like to pretend that all lockdowns are effective and virtuous.
If you are advocating Zero Covid, then go right ahead. Pretending a land border with thousands of daily crossings doesn’t exist, that we don’t have roll on/roll off trucking etc. has just as many holes in it.