Was mentioned by Higgins in the episode "Under World" (watched it last night). When I heard the name, it made me laugh as it's the name of one of the characters on tv's Rug Rats cartoon and The Wild Thornberry movie. Remember the cartoon from when my son was younger.
I doubt it, but you never know. The creators would have to have been some seriously hardcore Magnum fans to use such an obscure reference as inspiration for a character's name!
11 years later, I'm sitting here watching Season 5 Episode 89 "Underworld" and I hear Higgins telling a comatose T.C about his wild war stories with a "Nigel Thornberry." I'm glad I wasn't the only curious about this. At least not in the last decade. haha.
And, who knows, maybe we really did stumble on something that inspired the Nickelodeon writers.