A very good point.But that's exactly what makes the Western world different from the said Islamic countries,yes?The freedom factor. Besides Hitler is dead and gone and will have no idea people are buying his book,nor benefit from it, where-see somebody like Salman Rushdie, though not even half as deadly as Hitler, is very much alive and kicking and will likely benefit from the sales of his books hence those who hate his works and him, would not like him to prosper under their watch.
That said personally I feel its even a good thing to know what goes on in the mind of Mr "Satanic Verses" Rushdie's as well. It helps us know the other side and knowledge in cases like this is essential in order to avoid further disasters. So we see the warning signals early on before it turns a menace.
The way I see it is the recommendation was for only reading the book not supporting the cause.