Bit of a reach from there to "teaching aikido = teaching shinto", don't you think? I mean, not too much of a reach for a person who's looking to find something to object to, but for the rest of us, again, why should O-Sensei's personal belief system matter? Are you saying that in order to study aikido, one must also have Shinto beliefs? If so, that's your statement; it doesn't appear to be O-Sensei's statement.
I'm not sure that O-sensei was able to separate the two things. I'm not saying that you must have Shinto beliefs, but I would say that you need some kind of understanding of them if you have any interest in trying to understand anything that the Founder said or wrote.