You are still missing the point. R2 will have many changes in API, which means apps will basically need to be rewritten. Not ported, but rewritten. So if we don't have a 64bit R1, it means the only option for people who want 64 bit for the next few years would be an unfinished system with no apps.
So, we need some migration path. A possible one is having a 64bit R1, and somehow have R2 able to run 64bit R1 apps (with a compatibility layer). We have most of the support for that as we already know how to do hybrid builds.
The option you suggest is a 32bit only R1. In that case, R2 would need to run 32bit apps to provide a migration path. Which means we would need to support 32bit up until R2 end of life, and moreover be able to run 32bit apps on top of a 64bit kernel, something we don't have support for yet. So in the end, more work for a more legacy system.
Lets rather make 64bit official as soon as we can, so we can completely drop 32bit support as soon as reasonably possible.