He marked the occasion by scoring his team's 10th try of the match thanks to a trademark darting run in the 79th minute.
"What a career Rob has had and what an influential player he has been. He'll continue to be influential," McDermott told reporters.
"The role he plays with us, he adapts it here and there, but he's still very effective and that last try he scored he has been doing that for years. Those jinky little runs are hard to defend.
"He's not the biggest in the world and he cops for a lot of punishment. He gets battered around, but he's a game fellow."
Leeds are now top of the Super League table, with 11 points from six games.