I believe you already answered your question, merely by guessing.

[ Silco knew who was in Piltover, after all. He'd had to manipulate them, and listening to Marcus prattle on at times about the dangerous ones gave him a bit of an insight. Mind, while Silco thought she was dangerous, it was a personal dangerous. He was the type to take things personally, after all. Planning revenge for half a decade just...did that to people. ] ]

She's made a nice little distraction from the frivolities to play enforcer.