That said there certainly are some other instances in which a legitimate case for reparations might be made, injustices perpetrated by the legal person of the US government against identifiable victims with (depending on time elapsed) broadly identifiable heirs who have demonstrably suffered in consequence. Native Americans are an obvious example. So in that case - America's second worst domestic sin - and others like it, your argument seems to be something along the lines of "We must not advocate for justice in the case of black Americans, because if we do it might lead to demands for
even more justice!" We must not demand accountability and amends for America's greatest domestic crime, because that raises the question of its lesser crimes also. We must not imprison the murderers, because we'll never be able to imprison all the thieves.
Maybe it's just me, but it doesn't seem like a particularly rational argument
Even if it were true that accountability and amends for
every single instance of its wrongdoing is impossible or that it would bankrupt America (which you obviously haven't proven, or even coherently attempted to argue), how is that a reason to argue that no wrongdoing whatsoever should be addressed? That not even its greatest domestic crime should be addressed? The world is never going to be perfect, justice is never going to be perfect, governments are never going to be perfect; but it seems to me that people who are even minimally-interested in issues like justice and good governance should aim to address the greatest issues at the very least.