I doubt social security is really an important issue, most immigrants come here to work, often times to send money home, that's the real issue here. In 2016 canada created ~215,000 new jobs, of which 155,000 were part time and ~130,000 were service jobs (I excluded construction services and wholesale trade, i just included shitty service jobs). Those were new jobs, while high paying industry like manufacturing lost 70,000. With canada taking ~320,000 immigrants in 2016 and having a natural population growth of ~100,000 year to year, how do we expect to keep the population employed, and employed in jobs with a livable wage.

The median Canadian only makes 27,000 per year and with hundreds of thousands of low skill immigrants moving here we will see the value of labour and number of full time jobs continue to fall. It works for immigrant families, living 10 people to a 2 bedroom apartment (aka my neighbours), but canadian citizens are only going to suffer from this immigration policy.