And just to add a more solid case, Ikeda went outside to train with Ushiro to get the skills.
That's not entirely true. Ikeda and I are good friends. We've taught together and discussed this topic several times. Ikeda had very good internal skills long before he met Ushiro Kenji. It was his previous exposure to internal skills that allowed him to recognize them in others and to pursue them wherever he found them.
I will agree that Ikeda is perhaps outside the norm in the aikido community as he is willing to venture outside the box to evaluate tools he can use to improve his expression of Aikido. That's how Ushiro Kenji ended up being invited to Ikeda's Summer Camp.