No, they'd lose anticipated value of the debt repayment compared to other goods and services if the gov did that without other compensatory policy, but get all the money they expected.
> The expectation that they're _not_ going to print money to repay debt is part of why it's so safe.
You are confusing “why dollars are safe” with “why US government debt is safe”.
The expectation that the money supply will be managed, in total, for stability and reasonably low inflation is why dollars are safe. (The expectation of not monetizing the debt, to the extent it is relevant at all, is relevant here.)
The expectation that the US government will not in any case default is why, among dollar-denominated instruments, US government debt is considered almost as safe as actual dollars.
No, I'm correctly characterizing inflation risk, which—by definition—does not involve losing money you had or anticipated.
> You can't just wish it away by saying it's "why dollars are safe".
No, the perceived lack of significant actual inflation risk is why dollars are considered safe, not the risk category itself.
This is absolutely not the reason they're considered low risk. If the USG tried to repay its debts by printing money, debtholders uninsured against inflation would lose tons of money. The expectation that they're _not_ going to print money to repay debt is part of why it's so safe.