This bass will be strung with nylon tapewounds - they do not conduct electricity due to a plastic coating, and a bridge ground would not help.
What if the original owner/buyer sells it to somebody. They decide to change the pups and strings. Whole new ball game here.
Ok I get that you are going to ground 1 string and use the zero fret as a "buss bar" so to speak, my 20 years of being an electrical designer sends up some red flags on this. Just sayin.