"Decision 1: “Do I signal?” Costless. Decision 2: “Do I actually filter spam from my blocks?” It has cost (~0.1% revenue). But bytime you face it, you’ve already publicly signalled support. By making Decision 1 easy, BIP-110 pulls miners through gate before they face Decision 2."

https://blockspaceweekly.substack.com/p/issue-11-who-will-signal-first