Altogether you have seemed to miss my point. If we were to wonder why O Sensei did not encourage his non-Japanese students to become part of his religion, then the answer lies partly in the fact that the Oomoto kyo did not ecourage this at the time. Even if they may have made exceptions to that rule, it does not change that fact. The fact that Oomoto kyo had been active on reaching out on a bigger scale (Paris, Brasil) around 1925 is not relevant. O Sensei did not have foreign students at that time.
I wasn't talking about Ueshiba at all, just making a point about Omoto-kyo. It's not so much that they discourage it as much as they don't make efforts to evangelize, and only a small portion of the materials are available outside of Japanese or Esperanto. Anyway - foreign members were and are permitted in Omoto-kyo.
OTOH, it wasn't just non-Japanese students - he didn't encourage Japanese students to join his religion either.