"There is no moral justification for the government setting a retirement age, but they are able to. So it doesn't matter."
There is a minimum age to collect old age benefits from the government. The justification for that should be obvious.
The justification is to force people to work until they are too old to do so. Then steal whatever they have left with medical bills and price hikes on necessities.
Social Security constitutionality was ruled on just months after the 'switch in time that saved 9' associated with a threatening to pack the courts and evade the checks and balances built into our "democracy." They ruled it was covered under 'general welfare' in a way that was totally historically inaccurate.
Furthermore, FDR and congress purposefully had it packaged in an omnibus style bill to evade democratic scrutiny over the individual portions, by purposefully torpedoing other aid to needy individuals if SS didn't pass, so that lawmakers wouldn't be able to vote on democratic view of SS but rather being damned in a catch-22 where they'd be accused of not helping out the needy in other ways.
Basically the whole thing was designed to not only evade democracy but also the constitution.
[] Recollections of the New Deal, by Thomas H. Eliot, pp. 102-115 (Northeastern University Press, Boston, 1991).
Actually, the justification is to prevent old people from having to work. Retirement didn't really exist until the creation of pension systems in the late 19th century, and the modern social security system was a poverty alleviation measure introduced in the 1930s. Hell, social security was initially resented by older workers because of the cover it gave employers for firing them for being too old.
To make an overly dramatic analogy, if you were kidnapped and asked why the kidnapper was able to hold you against your will, the answer is because they've chained you up and they have the gun, and so on. That's literally the answer to why. The fact that what they're doing is morally wrong is completely irrelevant.
The government makes a moral justification of a savings plan but then when we dig down to it it's all ether and really just a scheme for bond rate arbitrage for the government.
The point isn't that might makes right is false, it's that the moral justification is a facade.