There are many white/European Muslims, especially in Southeast Europe (many Bosniaks, Albanians, etc.).
It is true that Albanians and other refugees from the Balkans to make up a portion of Muslim migration to Western and Central Europe. I wouldn't have considered Albanians white, and, even if they are, I'm fairly sure they suffer from racism from Western Europeans as much as North Africans and Arabs.
This law still seems to stem predominantly from the ultraconservative right's growing fears of these immigrants and their 'effects' on society. Maybe it is not specifically directed at one group, maybe it does stem from nationalism as well, but I do believe racism is going on here, whether hidden or public.
I agree its a dumb law and I don't quite understand how they'd enforce it but I have not seen anything that suggests this law would impinge on the basic rights of Muslims. Minarets are not essential at all to the function of a mosque. They are symbols. No different than the crucifix on top of churches. If a church can operate without a crucifix, a mosque can operate without a minaret.
Nor are minarets required for the call to prayer, they have speakers for that. The days when guys climbed the tower and shouted out are long gone. And the Adhan is usually restricted outside the Islamic world by local noise ordinances and such. When was the last time you heard a mosque in Toronto blaring out a call to prayer through a loud speaker like you do in the Middle East? I am fairly sure that would not go down well at 5am in the morning in most Toronto neighbourhoods. Would you suggest that not allowing the Adhan in Toronto is a violation of the rights of Muslims?
No question though that the Swiss are violating the architectural rights of Muslims. But it's over the top to suggest that Muslims are having their freedom of religion curtailed.
If a law were to be past limiting church spires and bell towers, I do think that would cross the line of freedom of religion. I'm sure one could find a valid legal case for it. They are being impeded in their practices, specifically how they build their houses of worship. While I'm sure it is possible to build a mosque with a minaret, by limiting the Muslim communities' presence in Switzerland you are also sending a very negative message. Even if minarets only serve as a symbolic marker of a local Muslim community, it is serious discrimination to not allow them that.
I do think that immigrants of Muslim faith in Canada do not face an entirely peachy life. That said, out of all the Western nations, I believe that we offer them the most protection. Although per capita the amount of Muslims is about 1/3rd of that of Europe, in a 2007 CBC survey* members of that faith were found to be the most satisfied with their country in the West. The only country that came close was Spain, of which Canada was ahead by 5%. Without the same ghettos and lack of integration that occurs in Europe, one has to conclude that we have been more accommodating over the years.
*
http://www.cbc.ca/news/background/islam/muslim-survey.html