As I've mentioned before, one of the most bizarre phenomena of the age we live in is that people who quite clearly lack even a basic knowledge of Islam - a fact that could be established quite easily by asking them questions like "What are the hadith?", "What is the doctrine of abrogation?", "What are the five pillars of Islam?" - nonetheless fancy themselves expert Islamic theologians, entitled to lecture practising Muslims on the true nature of their faith. Here we have another example of it. The man whose words "You ain't no Muslim bruv" were seized on by the ruling class to defend their multicultural fantasy in the face of ongoing jihad attacks, including this one in the London underground, was himself not a Muslim (see article). He was security guard, probably not very well educated, but nonetheless sufficiently brainwashed by the Establishment media to exhibit the reflexively programmed response.
Trying to imagine the same thing occurring with other "religions", Buddhists being lectured on the true nature of Buddhism, Hindus being told what their own beliefs are, gives you an idea of how strange this practice really is. This kind of irrationality can only be produced by extreme cognitive dissonance: when people hold strong beliefs that are confronted by discordant facts, they try to explain away those facts, in increasingly absurd ways.