Sivo was simply unstoppable as the Rhinos roared clear at the top of the table on the back of a 10-minute burst towards the end of the second half that all but ended the hosts' run of six consecutive top-flight wins.
Sivo has pulled clear at the top of this season's try-scoring charts with 25 to his name in the league alone, and Arthur admitted: "I'm so pleased for him, he's such a likeable person and the boys love being around him.
"He's scoring a lot of tries but he's been working really hard on keeping his weight around 109 kilos. He hasn't got an ounce of fat on him - the leaner he can be the more we can get out of him and he's worked really hard on that."
Arthur was particularly pleased with the way his side shrugged off some relatively indifferent displays away from home to nail an 80-minute performance which makes them favourites to continue their march towards the League Leaders' Shield.
"Our away games haven't been as important as our home games so we just had to focus in the last couple of weeks about being more professional away from home, and we're getting closer to that tonight," added the former Parramatta mentor.
Sam Burgess had few complaints about the manner of his side's defeat and admitted he ended the night relieved the Rhinos had not seize their opportunities to make the final scoreline even more embarrassing for the hosts.
Burgess, the former South Sydney star, said: "I'm quite happy they didn't get to 50 points because at one point in the second half, with their style of play, everything was sticking, and there was a point where I thought 'this could get very dangerous'.
"I'm very happy we scrambled the game back, but we had a tough night and they made us pay. I didn't feel the half-time scoreline reflected the play but they made us pay in the second half. When they get in a mood like that they're very hard to handle."
