I'm sure their view is that those who don't agree with them cannot be muslims.

I'm not sure who "they" are that you're referring to.  The Salafis?  Yes, we have established that they think basically nobody is really Muslim except them, but they are also very decidedly a minority.  I think you're misunderstanding my point, which is that the people I most often hear saying things about Islam being incompatible with democracy are Islam-bashers and Islamophobes.