To be honest, I can't see why you'd feel that way. As you recognise later in that same post, religious adherence is memetic, not genetic. Birth rates are therefore fallacious to be either disappointed or thrilled about.
True, we can make all kinds of nuances, but I would be fooling myself if I thought a "10 times faster" rise in Muslims wouldn't actually mean more practicing politically-aware Muslims as well. We'll simply have more people walking around who are debating whether being friends with non-Muslims is halal, or whether voting isn't kufr, or who believe their own government is an enemy of Islam, or who believe making cartoons about Muhammed should be outlawed. They will have many issues with the current liberal, atheist 'hedonistic' way of life in Western European countries, one which I value strongly.
Note, I of course don't blame some Muslims for believing what they believe, but I think social strife will become more likely because of this. I don't want to play a blame game, 'Islamophobia' and racism among non-Muslims is a real issue as well and as much to blame as well.
I just want two things:
1. Keep our liberal ideals intact
2. Prevent social strife