I think the deciding factor is whether you primarily practice aikido as a philosophy or a martial art. If you fall into the latter category then it seems ridiculous to liken aikido to pacifism as the very definition of the word is an opposition to war or violence as a means of resolving disputes. If you're a member of the camp that believes every fight has two losers than YOU may be a pacifist, however, in my opinion, aikido (or any martial art for that matter) by very definition is not pacifism. Ghandi was a pacifist. Jesus was a pacifist. OSensei doesn't fit the title as I see it.
Well, that's my two cents, anyway. Also the first two cents I've posted since I finally registered a username.