Not sure I agree with this - a wide part of the 'Israel debate' in the UK is clearly anti-semitic, or at the very least, results in anti-semitic sentiments being shared and promoted among anti-Israel campaigners. This may sadly be an unavoidable consequence of having Israel be the country that people are protesting against (sadly - from my East London based facebook feed it appears that way), but if we allow our elected officials to get away with such sentiments then the problem has no chance of improving.
Splitting the two (anti-semitism, and anti-Israel) is a very important issue for the Labour party, and coming down hard on people like Naz Shah is what has to be done to push us in the right direction.