Oh my god no I don't think you realize the staggering amount of sheer loathing Harley has for Thomas Elliot. He managed to get Joker on-board with his first plot to kill Batman, but when Harley tried to kill Batman-- to make Joker happy, no less, not out of personal vengeance— Joker told her nobody was allowed to kill Batman except for him and then pushed her out a window. She hates Tommy so much for it, even if it wasn't necessarily his fault. Not only that, but he was engaged to Peyton Riley, and even if he hadn’t gotten off scott-free where Harley had nearly died for trying to kill Batman, she would have hated him just for being so closely associated to Peyton. Harley sees them both as cowardly, shallow people who pervert and destroy The Way Things Are to serve their own selfish needs. He waltzed into her world and fucked with the fabric of her reality, and wasn't even punished for it. There are no words in the English language to describe the sheer amount of burning rage this man inspires in Harley.