I'm almost certain it was Dayvv Brooks, who also named the koopalings. It would fit the koopalings' general musician-theme if he were named after Jon "Bowzer" Bauman of Sha Na Na fame; as would Bauman's famous "tough guy" posturing fit Bowser.
I haven't bothered asking him myself because I'm sure I wouldn't get a response, but you're free to try. Be sure to ask him about the names "podaboo" and "lakitu" while you're at it.