I believe Robbie's score is 100% legit and have no reason to believe a voltage of 4.7 would cause a change in RNG. There are a variety of reasons why, but the main one is that the voltage would have to specifically influence the memory address responsible for the RNG timer and nothing else in order to directly influence the randomness. On top of that, it would have to only occur on the barrel boards and no other stage according to Robbie's testimony. It would be nice if the video had sound, but there's nothing in the video itself that indicates direct cheating. With all of that said, I congratulate Robbie on his achievement.
However, Robbie believes that he is cheating using this method. Admitting to attempting (whether successful or not) to gain an advantage through hardware modification is very dubious with regards to the competitive spirit. Robbie is no stranger to violations of the competitive spirit given the images he currently has on his streamed games, or his ban from Kong League for harassment of league members and perceived homophobic comments. It is sad that the best player in the world chooses to represent hate considering how different things used to be.
I think it's very clear why Robbie chose to submit to both Donkey Kong Forum and Twin Galaxies -- Places that he views as utterly abhorrent: He wants to prove a point. He knew that the score would be rejected (at least on DKF) based on his actions and public comments, and this will make him a martyr in his own circle.
Bravo.