As for what I understand aiki to mean, I suppose a large part of it is harmonising forces. Whether those forces are within, or come from an attacker or are metaphorical or whatever is up to the interpreter. In any case, I am yet to be convinced that hitting someone in the head is particularly aiki. I am, however, willing to be convinced. Could you explain how you see it?
Instead of a strike, consider a wrist grab. Consider using the contact point at the wrist to connect to nage's spine through his arm, and using that connection to take him down, or to immobilize him for a strike. Is that a manifestation of "harmonizing forces?" As I see it, yes, absolutely.
A strike is simply a more explosive version of the same idea.