I do understand the motives of the left in defending Islam. There are people who have been attacked simply for being Muslims, not for anything they have actually done, and other people who are not even Muslims but who can be mistaken for Muslims (such as Sikhs) and who also get attacked. Religious persecution is wrong. That is why in the US, where there is no persecution of Christianity (despite the effort by some Christians to claim that there is) but there is persecution of Muslims, the left wing therefore mobilizes in defense of those Muslims. That is not intended as an endorsement of the religion.

At the same time, the political left wing has to be careful about what they are doing. The basis of left wing ideology is the importance of human rights. Islam has no respect for the civil rights of non-Muslims, or of women, or of homosexuals. It does not respect freedom of speech (and indeed, Islam is violently opposed to freedom of speech, such as in the famous case of Charlie Hebdo) or freedom of religion (people have been executed for expressing non-Muslim beliefs on facebook or in a blog) nor does Islam support freedom of any kind. Short of moving to North Korea, you could not find a more repressive society than a Muslim theocracy.

The left wing, therefore, if it is to be true to its own principles, must avoid encouraging the persecution of Muslims (most of whom are not guilty of any crime) but also must avoid encouraging the repressive ideology of Islam itself.

The left wing does make strange alliances. The ACLU famously defends neo-Nazi organizations, because they too have rights, even though they are entirely dedicated to violating the rights of others. They still enjoy freedom of speech in the US (although not in Canada, where hate speech is illegal). These kinds of alliances can be very tricky.