Your ISP example doesn't work because it's not about the "junk traffic". Sending "junk" to your ISP wastes a little bit of bandwidth but doesn't meaningfully damage their business model (might make them money depending on the pricing model). The goal of this plugin is literally to destroy most of the value that ad networks provide (namely targeted advertising). This doesn't simply remove a user from advertising networks dataset (like an ad blocker) but poisons the dataset. This harms ad networks and everyone who relies on them to fund their work.

Blocking users who run AdNauseum does seem entirely appropriate to me. Blocking the plugin from Chrome also seems appropriate to me.