Couple of comments about 'head down' instrument work in single-seaters while VMC and also comments about infallible airspace....
This single fighter 'instrument approach practice' scenario struck me as somewhat unusual in that in cases of truly flying instrument practice in the single-seaters, we normally provided for a safety chase. If the type had a two-seater, this was the preferred instrument trainer in the fighters I'm familiar with, the safety pilot being in the front seat. However, even in the single-seater, you do not necessarily have to be 'head down' as such to fly instruments.
With respect to the P/D radar, even the early F-16A radar did not have a problem with ground clutter and was always utilized to provide traffic situation awareness when 'cruising' about if serviceable. There are certain isolated situations where a return may temporarily not be displayed however.
The mil has spent a lot of money on Auto-GCAS to prevent CFIT, but evidently don't feel the same urgency with respect to TCAS.
ADS-B 'out' will be an improvement, but still provides overall situation awareness to the controllers only. In a perfect world everyone would also have ADS-B 'in'. Don't hold your breath.
And I personally think 'VFR non-participation' should always be available to GA, it's the American way, but you takes your chances....and potentially someone else's.