[T}here is no reason at all for us, indeed there is no real possibility for us, to be multiculturalists at home, if by multiculturalism is meant the granting of legal and social equality, recognition and protection to all the customs, traditions, beliefs and practices whatsoever of immigrants, as if multiculturalism were merely a kind of fusion cooking[...]
The reason is because culture is complex, and hard to understand. So immigrants must inevitably adapt to the culture they enter into.
It's all hard to deny, but also hard to see as a serious attack on multiculturalism as she is in fact practiced.
Let's pull the passage apart.
"Legal equality" cannot, of course, be granted to all practices, since some practices may violate the rights of other people. But in a liberal society, it is quite possible to grant legal equality to peaceful customs, traditions and beliefs. We do that indeed.
"Social equality" could mean one of two things. It could mean that there is a social taboo against being rude about people's customs, traditions and beliefs. Or it could mean that all traditions -- from the Anglo to the K'ung! -- are equally prominent in the society. Again, the first is perfectly possible, and largely accomplished in Vancouver or Toronto. The second is, no doubt, impossible, but for that very reason, not something to worry about.
Multiculturalism is just the fact of ethnic diversity plus the norm of liberal tolerance. Are there tensions when that fact and this norm are put together? Sure. Are these tensions unmanageable? Toronto says otherwise.