He did receive credit and he was paid by ILM. He also became a visual effects supervisor. Maybe he feels he didn't receive enough of the credit compared to Denn

He did receive credit and he was paid by ILM. He also became a visual effects supervisor. Maybe he feels he didn't receive enough of the credit compared to Dennis Muren and Phil Tippet, but he was also not in charge of the show. He did end up in many behind the scenes interviews. If anyone didn't get enough credit, it was probably the texture painters, lookdev artists, shader writers and lighters who actually made the dinosaurs look realistic.