TSP G Fund as the only Fixed Income Investment (opens in new tab)

Here's something I'm debating and hoping the collective brain trust of the HD community can push me in the right direction. As a retired Fed, I have access to the Thrift Saving Plan G Fund. For those not familiar, it's basically a high yield savings account on steroids. It pays rates comparable to medium/long-term Treasuries but has no default risk, duration risk, or interest rate risk. It only pays interest and can never fall in value. There is no comparable investment available in the priva...