I believe this to be a false statement indeed, seeing as the nine tailed beast together=Juubi right? Why would one Biju in its perfect form even reach more than a fraction of the Juubi's power?
It just doesn't make sense to me.. Hypothetically, all of the tailed beast could have reached a "perfect" form if each of their host had committed the same acts as Naruto, and went through similar situations.. Does this also mean (due to your theory) that they would be close to the Juubi's power? I don't think so.
OT: No, I don't think it's plausible.