I've seen that tactic to try to discredit real, valid concerns with immigration, either by lumping it with racism (which definitely exists, but is not the only argument against unfettered immigration), or by pretending something else is the problem (something else may also be a problem, but that doesn't make the problems that people are worried about with high levels of immigration invalid).
In my understanding, the backlash against immigration in Canada is relatively recent, and it's basically caused by the fact that Canada took in a huge number of immigrants, historically speaking, in recent years. This results in:
1. People feeling likes many immigrant communities are creating enclaves instead of adopting the culture of Canada. 2. Many recent immigrants are unskilled, resulting in a larger burden on provincial-based social services.
When you couple that with astronomical housing prices and a stagnant economy with rising unemployment where many people see less opportunity, it's not hard to see why citizens are demanding lower rates of immigration.