What you describe in your family dynamic applies so minimally as to be a strawman representation of the far more complex systems at play governing the dynamic between the federal and state economies.
And pensions are just one way a municipality can take on debt. Even if you force them to lock up savings ready for their employees' retirement, they can still load up on debts with municipal bonds, signing long-term contracts, delaying payments to suppliers, and suchlike.
Have there been any examples where a federal bail-out has been accompanied by legal mandates, and it's been successful?
And even if federal pension fund bail-outs bring with them strict rules that prevent them recurring in the same city, unless you can impose such rules on other cities without giving them bail-out money, you've still got the issue that paying off City A's unmanageable pension deficit will encourage City B, which is struggling with its pension deficit, to make it truly unmanageable to get a bail-out.
[1] https://www.cnbc.com/id/45018432 [2] https://www.bloomberg.com/opinion/articles/2018-04-04/congre...
The problems are (a) he might just get into debt again, for the same reasons he did the first time; and (b) his brothers and sisters might be upset I gave him $$$ for fucking up, or even decide it's clever to emulate him.
In other words, by paying off something I can afford, I would fear triggering a chain reaction leading to something I can't afford.