What you are calling a "desecrated Christian Ichthus symbol" could also be taken as a symbol that implies Christianity and the ToE are compatible and complimentary. This is what many Christian religions think.
It seems to me it's all in the eye of the beholder, or the offended.
So does the cross, but does that mean that Andres Serrano didn't desecrate a Christian Symbol when he placed it in a jar of urine?
The intent of the Darwin Fish was to stick it to the Fundamentalist Christians. Just like the Kansas professor's intent was to stick it to the fundies by teaching a class called "Special Topics in Religion: Intelligent Design, Creationisms and other Religious Mythologies."
The intent of the Darwin Fish is to make Christians the object of derision. To wear such an object while teaching classes at a public school is a disgrace. Teaching a class at a publicly funded Taxpayer supported University while wearing a Christian Ichthus T-Shirt would obviously be frowned upon by the Administration. But if you desecrate that symbol and use it as an object of Christian intolerance, then that is just fine.
I just dare any of these so-called enlightened professors to publicly treat Islam with the same derision that they publicly treat Fundamentalists Christians. They might not lose their tenure, but they very well might lose their lives. That is why they won't do it. They equate Fundamentalist Christians with Fundamentalist Islamicists, but when it comes down to brass tacks, they know full well they have nothing to fear from the Christians and plenty to fear from the Muslims.