I believe its an inevitable choice.
Imagine, all of a sudden, in 2-3 seasons time, ten us or chinese or czech etc teams participating in B3. Not good.
Also, being able to go to a micronation and target B3 in no time, would make several good teams that are stuck in division I and II in their respective countries, turning their well founded teams into farms and making their secondary team, primary.
That would cause a decrease of quality in big nation leagues, a chaotic situation regarging all aspects of training and an under par B3 for many seasons.
Most of all, in this case, we're not speaking about secondary team, but two equal teams for the manager to decide what to do with them.
Straight away, this would be unfair and a huge disadvantage for the non-supporters, contadicting BB's philosophy.