Do you think leftists would meekly submit and refrain from criticizing the sect, or do you think they'd demand the authorities crack down on the new violent sect and further demand that their right to free speech not be impinged?
Leftists being leftists, they're using this Islam thing to try and suppress the free speech of people they don't like i.e. conservatives.
There are Christian sects that do exist that would oppose pictures of themselves or Jesus or God- as a practical example they assert that requiring a photo on a drivers license violates their religious freedom because it is a form of graven image, specifically prohibited by Exodus 20: 4-6.
The thing is, when they object to the photo requirement for a drivers license, they typically go to court to litigate the issue, as opposed to say shooting up the DMV as an expression of their deeply held religious belief.
And when these stories do hit the news, these individuals are typically portrayed as ultra-fringe fundamentalist nut jobs and their beliefs are dismissed out of hand, if not outright ridiculed by the media.