The strings ferrules on the rear bar of the bigsby works as a stop point for the strings. With a string through body config, you are simply moving the stop point a little further. Since the tremolo action works with the tension of the strings, it doesn't matter where the stop point is, as long as it's fixed.
Well, people find strings long enough for for 28" scale baritone guitars easy enough... what I see here though, is just an auto-string breaker. Every time you wiggle the bar, the part of the string right where it goes through that back bar is going to be wiggling at least 12 or 15 degrees - and they're already going to be coming up out of body holes at 25, 40 degrees? SNAP SNAP SNAP SNAP SNAP PING!
Some people have thought through this vibrato stuff. Not well, in my opinion - a vibrato that pulls the strings straight instead of angling them is a better beast - but still. Maybe I don't understand the idea.