Pension Plan Discount Rate

For the discount rate of a US company’s pension plan, I am confused by the idea that we can use safe long-term government bond total return as the discount rate for our liabilities? Why don’t we have to use a discount rate to represent the risk of these promised cash-flows, like we do say in the dividend discount model (ie a higher one, since the risk of this specific company is higher than that of the government’s)?

Thanks,

Because if the firm didn’t owe money to retirees, it would have invested that cash in a risk free asset.

Unless it invested the cash in something else.