Graham, I don't see how your understanding relates to historical facts?
And as someone who in all those years never was taught aikido as spiritual art I simply don't get your point. Loving peace and harmony, or, to use Brians word, being compassionate to me is not the same as spiritual. And, above all, is not unique to aikido.
Yes, this is what I think: Just different members of the familiy. Different characters, different biographies. But relatives.
They relate to spiritual historical facts.
If you haven't been taught then sure, thats all good. Hence your view on compassion.