Mature-age rookie Fuller darted over on the left side midway through the first half to score what appeared the opening try of Sunday's shootout for eighth spot at McDonald Jones Stadium.
But on closer inspection, the bunker ruled Dolphins second-rower Connelly Lemuelu had impacted the outside shoulder of Knights forward Brodie Jones and prevented him from reaching Fuller.
Newcastle ran in the next two tries and ultimately clinched the last spot in the top eight, crushing the Dolphins' hopes of a maiden finals berth in their second season.
Lemuelu had also contacted Jack Cogger with his run but impacted only the Knights' five-eighth's inside shoulder - not grounds for an obstruction because his passage to the ball had not been blocked.
At full-time, Benett suggested it was Cogger who had actually obstructed Jones and not Lemuelu, furious that the try had not stood.
Outgoing Dolphins coach Wayne Bennett has renewed calls to scrap the NRL's bunker review system. (Jono Searle/AAP PHOTOS)
"If that's where we're going we're in a fair bit of trouble because that's a try every week," said the outgoing Dolphins coach.
"The three defender (Cogger) committed our player who was running the inside shoulder, which is what he's supposed to do, and the four defender (Jones) ran into him and they said he (Lemuelu) obstructed him.
"If that's the case there will be no more of those tries scored.
"The four defender will run straight into the guy running through because he knows he's going to get a penalty ... it's just crazy. I feel sad for the teams going forward in the next four weeks because someone else is going to pay the price for it."
An ardent critic of the bunker in the past, Bennett took another swipe at the video review system after his last game before rejoining South Sydney for the 2025 season.
"We get rid of it (the bunker)," he said.
"The refs used to get it wrong in the past, but we got on with life.Â
"We didn't analyse it like we're doing today. (NRL football boss) Graham Annesley gets up every second week and apologises for something that went wrong."
Bennett insisted his frustration was not due to the result that precluded his side from finals
"I'm not complaining about the fact we got beaten here because it was a tough game. It could have went either way and we both played our hearts out," he said.
"That's not the problem."
