There is a difference between "is it right to ..." and "do I have a right to ...".
I have the right to insult someone I am soliciting for a favor. On the other hand, if the insult would result in the favor being denied, would that insult was the right thing to do?
We certainly have the right to say what we think is true about Islam, no matter how Muslims might react to it. But is it always right to do so? Those who think Islam is a despicable religion might think some speech disparaging Islam is true and may defend, even celebrate such disparaging speech. But given our need to work with Muslim majority nations for out own interests, is such speech the right speech to make?