Lots of people I know and respect insist that Islam is not a religion. So his view here is not unique or unsupported. Ultimately it boils down to what one calls a religion of course.
Islam has a very strong component of faith, so much so that thinking is not recommended as it threatens that faith, and has a supernatural element to it as well, however not the way Judaism or Christianity does. Both of those believe that God will do his own dirty work. Islam believes that the followers of Mohamed must do ‘Allah’s’ work for him. This is a fairly crucial distinction actually.
For my money, Islam is indeed a religion. One can always define a thing to include or exclude whatever one likes and as many people do like religion, I can see how they would wish to define it in some way as to exclude islam.
But lets face it.
Islam is a religion. Just a really shitty one.