aikido has a few things in common with Noh, which is very religious, so maybe that's why someone said that. It's probably just one person's interpretation though.
For example, in Noh, you keep your hips low, pivot on your feet with a strong sense of your center, when you walk you slide your feet (suriashi), stuff like that. If you watch it, it can remind you of old videos of Osensei with a fan in his hand.
maybe that and Osensei says aikido practice is misogi or purification, maybe.