Why EFF did this is to get journalists to get a story to write about the issue. Nobody involved cared whether anyone at Apple saw it.
Except exactly 0 articles were written outside of them writing an article about it themselves. Where is the 'lots of publicity'? They generate just as much when they write and article about anything in general.
It was also covered by MacRumors: https://www.macrumors.com/2021/09/24/eff-apple-park-banner-c...
But this on-device scanning proposes to undermine that.
Also strongly because Apple set itself up as a supervillian over right to repair & closed ecosystems - and as an IP bully cage fighter.