Using the term "racist" to describe someone posting,say, an anti-Muslim viewpoint is technically incorrect, inasmuch as racism refers to ethnicity and Muslims are not from one homogenous ethnic origin - so it is also lazy.
But - it is my feeling that at least some of the anti-muslim sentiment forcefully expressed in arguments and discussions is derived from a stereotypical view that all muslims are "brown-skinned foreigners" with extremist tendencies, and in those instances such sentiments are prejudicial and an example of lazy thinking.
Have just read what I think is an interesting article on just this topic. Have a read, if you feel like it - see what you think ;)
http://freethoughtblogs.com/crommunist/2013/05/29/is-criticism-of-islam-racist/
As to your last point - I do not think people are afraid to criticize islamic attitudes at all, although some institutions may be more circumspect in their language for fear of giving offence.
When the World Cup in Qatar comes a bit closer I would fully expect to see criticisms over human rights and equality issues being raised. There are already issues being reported over the unacceptable level of deaths from accidents during the building of the stadia in Qatar.
http://www.theguardian.com/world/2014/jan/24/qatar-2022-world-cup-185-nepalese-workers-died-2013