In case anyone was inclined to believe the above spin, the actual reason is that folks at seminars are asked not to discuss the material online in an attempt to keep it exclusive and monetizable. Most of the threads on this subject are marketing dressed up as discussion. Personally, I very much look forward to a frank discussion of training modalities instead.
This is so plain wrong it's hard to think how to respond. Dan never said ANYTHING like this at the seminar I attended in April. He certainly encouraged us to practise it with our students. I have never thought of this stuff as any kind of commercial "business" - mainly because in the modern world it is so hard to make much money out of it at all. This argument has gone round and round already on this site several times and has got pretty stale.
I am sure that there have been several quite comprehensive and open discussions on AikiWeb of the training exercises that both Dan and Mike Sigman teach. I spent a few minutes searching the forums earlier today, but gave up after a while - perhaps others have more patience (or a more organised bookmarking system).