Yeah , with your engine out and your only other option like some restricted area , say , under “live fire exercise” at the very same moment … I guess at that point you can safely say you were mean to go that day …
I would expect different judicial approach to signing waivers for a sightseeing flight around Grand Canyon vs an extremely hazardous trip to the bottom of the ocean in an experimental craft …
My understanding is that it was chosen because he wanted to fit more people inside and at certain size titanium only submersibles stop being practical because of weight limitations ( these things need to be picked up and handled by portable cranes etc )
Ok my post got canned because I suggested that basically unlimited presidential TFRs ( and their ground equivalents ) are a bad idea - it was too religious/political they say ..