The sentence above is from the article of Economist(link: https://www.economist.com/leaders/2018/12/13/the-real-lesson-from-theresa-mays-bruising-week).
I have a problem reading that sentence, especially with the expression "have been shown up for", and "they are" at the end of the sentence.
The expression 'show up', which is said idiom in my dictionary, means "to appear". But there are no such example i can find using the expression 'show up for'.
Second, the pharse 'they are' at the end of the sentence makes me feel that this sentence is somewhat incomplete. What is this for? I'm just guessing that it is to specify the 'obsession' is from 'the hardline Brexit bullies'.
Can anyone help me parse this sentence? I want to know the meaning and grammatical principle of these expressions.