Personally, I don't think talking is such a horrible thing. I was at a seminar at a school where there wasn't a lot of talking. Not a lot of laughing either, which bothered me. But anyway... We were working on a technique with which I was unfamiliar, and it wasn't happening for me. Rather than roll, my uke (yondan or godan, and dojo-cho of that school) would just run a few steps. I watched her with other students, and she'd fall when they got it right, and when she threw me, there was no running out. So obviously the problem was me. After my second go round without a throw, I said "What am I missing here?" She muttered "What are we all missing?" I thought that was a really crappy answer. Obviously she wasn't missing it. So no help there. Then after a couple more go rounds she stood and turned her hips a couple times. OK, so I'm not turning my hips? When? Still no help. Never once got the technique right. A couple weeks later I thought I might have caught on, but by that time I was home and the only people were junior to me, so I can't be sure that I really got it. If she'd just said "at this point in the technique, try doing this a little better," THEN did that hip turning thing, I would have gotten it in a second.
Another thing about that whole mute sempai thing is that it discourages questions. I don't think that's a good thing. When people are left to figure stuff out for themselves, then their understanding of Aikido is going to be limited to what they can figure out for themselves. I recently made a correction to the way I'd been teaching a sword technique. When I demonstrated it, I asked (as I always do after demonstrating a technique) "Any questions?" My senior student's hand immediatley shot up and he asked "Why?" So I told him. Later I thought that it might be pretty rare for a senior student to openly question the teacher like that, but that's the way I run things. I don't think I'm good enough to be shrouded in an air of mistique (speaking of that, I really liked the X-Men movie. Favorite line: "It's all right, it's me." "Prove it." "You're a dick." "Okay."), and by allowing the students to feel intellectually free, I have to stay on my toes. My answer to a question has never been "because that's how we do it." A couple times it's been "I'll get back to you," like when a student asked what I meant by spiritual growth. That was a tough one. But they know that everything we do has a reason. I don't think they would if I allowed no talking.
Just my unqualified opinion.