If your spring breaks you might want to consider going a bit easier on the Bigsby dive bombing or consider a career as an arm wrestler! For the life of me i cant imagine why someone who doesnt use their Bigsby needs to render it useless.If your spring breaks and the arm is flapping around, problem solved until you get a new spring.
If a player doesn't (ever) want to use the Bigsby vibrato on their Gretsch guitar, they should replace it with a static tailpiece, instead of using a disarmed Bigsby purely as a decoration.
I wouldn't do it, but it isn't necessarily a bad idea. Locking the Bigsby will make string-bends easier. It takes more effort to bend strings on a Bigsby-equipped guitar, because some of the effort goes into compressing the spring. I find it noticeably easier to bend strings on my one hardtail guitar.
If you don't want to use the Bigsby, and you don't want to modify the guitar by replacing the tailpiece, this isn't a bad solution.
Not that I'd ever take the springs out of my own Bigsbys. They're too much fun to use!