I tried to play around with your patch. It generates the desired file indeed. I though, as far as I am running build scripts, I can try to generate "compromise" .tab file, like for 5-10 years history. But apparently this is not the case and zonenow.tab is manually crafted and now.ck just checks its correctness. Please tell me if I am wrong.
You can see the answers to those questions by looking in now.ck.
Yes, I can see that all members of equivalence class in now.ck are equal, however, I can detect main one by the presence in zonenow.tab file.
The proposal is to include the patch, but not the artifact.
This kind of artifact may be useful in general. Besides "migrating from 1970 to now" case, it may serve purpose of "normalization-to-now" of "1970-timezone" coming from external source, e. g. user browser. Maybe some format more friendly than equivalence classes will be more convenient (close to generated Link-table, like we have in backward file). In general zonenow.tab covers a very common use case indeed, but it's harder to use without mapping from 1970-based timezones. So maybe you can consider shipping this kind of artifact as well.