That's nice but entirely irrelevant.
If you were 100% allocated in TSP G Fund and Treasury yields spiked across the curve, your account balance never goes down and you could withdrawal the entire amount at any time without losing a single penny.
If you were 100% allocated in 10-yr T-notes and Treasury yields spiked across the curve, well...you'd be swallowing a substantial loss proportional to your unhedged duration exposure if you were either to liquidate your position before maturity or before yields normalize.
This[1] is what you don't understand.