I think the question is - can aikido be spiritual without its martial aspect? For me, I would agree that it can't, although I have learnt alot about aikido from those who think otherwise.
The accepting 90% of the attack and the life/death aspect of aikido to me is an important illustration of trying to understand life in a buddhist sense. Also it seperates the armchair philosophy from actual practise of form and physicality (joining thought with reality). For me though, it contains within it a humerous irony, because through practising a self-defence you can loose fear of death, and thus not require a 'self-defence' except for spiritual practise.