Roosvelt, you've misquoted me, leaving out the main point of the sentence. My main point there was that people should not be training in a manner that recklessly endangers their training partners.
Also, it's relatively easy to stop many/most aikido techniques if you are at all strong and know what's coming. If an uke blocks a given technique, I might not be able to continue with that same technique/strategy, but there's probably another one that will work. That's what henkawaza's all about.