Re: dealing with uke from hell
Saotome Shihan says that if you're not allowed to hit uke, uke knows what you're going to do, and you're not allowed to change it, any aikido technique can be blocked. (I think Ledyard Sensei quoted him in the article referenced by the OP.)
In our dojo, it's fine to show uke gently why the way they've chosen to block a technique leaves them open to atemi. It's fine to show how it invites an alternate technique too. But these days, unless I care for them enough to be training them, I generally take it as a challenge to see what I can do with the situation as presented.