"So how did the hysteria extend to [All] Glocks kb; they are virtual hand grenades which will fire out of battery, etc., et yada...."
How does ANY rumor get started?
Part of it is fomented by people misunderstanding what they've heard, from a friend of a friend of a friend of a friend.
I also have absolutely NO doubt that a lot of it was spread by the true Glock Haters, people who are so offended at the thought of a polymer gun actually gaining public acceptance that they will stoop to any level, repeat any lie, cast any aspersion, necessary to make them feel as if they are doing their part of saving (pick any that apply) the American gun industry, steel guns, the 1911-A1 (God's own handgun), etc.