I believe, based on some of the conversations above, that the reason Shinzon used B4 as a lure for Picard and the Enterprise was because of Tasha's relationship with Data in the Naked Now, and what she told Sela about it before she was executed.
I sincerely doubt that the events in "The Naked Now" happened in the alternate war timeline.
And anyway, it's clear that Shinzon used B-4 as a lure because he knew Data was serving with Picard, and that Picard would go to Kolarus on Data's behalf to find another Soong-type android.