Ok, I apologize for calling your opinion ridiculous. I just do not agree with it.
I am not going to insist that you agree with me.
How do you know this "happens all the time?"
Because there are teams of people in the white house whose entire jobs are to make sure things like this don't happen (yes, I know this). There are teams of people in commands, agencies, etc to make sure things like this don't happen and their representatives are sent ahead fully knowledgable about how to greet people (at the very least). We have one here in our command.
They check the list of attending and research them to see if the FL needs to know anything. Since this man is well known (it seems, I have no clue who he is as it's not my job to) for his religious convictions, she should have been told that.
I do not think the FL should have to remember one person whom she should not shake hands with out of 100 that will. I do not think that is the responsibility of a visiting head-of-state.
Why not? As FL, she needs to make sure that any interaction with any foriegn dignitary goes as smoothly as possible. And it is not as if the FL doesn't have resources available to her to make this known. And, recognizing one face out of 100 wouldn't be that hard if she were told ahead of time.
It is the responsibility of a diplomat, however, to know how to politely decline to shake someone's hand (and not to whine about it afterwards).
This is very true. It is the responsibility of any diplomat to handle any hickups that may occur with continued dignity.