It appears you are correct - I stand corrected. This from a Talkbass poster, who sounds like they know what they're talking about - no guarantee I know! Also an earlier thread from BC too.
Bunny Brunel might have had a hand in testing the Yamaha BB series, along with the likes of Abe Laboriel, Nathan East, Lee Sklar, and a bunch of other session guys, but as I've understood it, John Carruthers developed the "Big Body" series basses for Yamaha, with input from all those early testers. It was not Bunny's design, or named for Bunny Brunel.